What causes subcutaneous ticks to appear?

Understanding Subcutaneous Ticks

What are Subcutaneous Ticks?

Types of Subcutaneous Mites

Subcutaneous mites represent a distinct group of arachnids that embed within the dermal layers of mammals, often producing localized inflammation and tissue reaction. Their presence results from direct skin contact with infested environments, host grooming habits, or accidental transfer from animal reservoirs. Understanding the specific taxa involved clarifies diagnostic and therapeutic approaches.

Dermanyssus gallinae (poultry mite) – primarily a ectoparasite of birds; occasional human infestation occurs when mites penetrate the epidermis and migrate deeper, especially in enclosed, poorly ventilated spaces.
Sarcoptes scabiei (scabies mite) – burrows into the stratum corneum but can extend into the superficial dermis, creating subcutaneous nodules that persist after the initial infestation.
Demodex folliculorum and Demodex brevis – inhabit hair follicles and sebaceous glands; dense populations may provoke cystic formations beneath the skin surface.
Trombiculidae larvae (chiggers) – attach to the epidermis, inject digestive enzymes, and may be driven into the superficial dermis, resulting in palpable papules.
Sarcoptiform mites (e.g., Psoroptes, Chorioptes) – typically affect livestock but can cause subdermal lesions in humans following direct contact with infested animals.

Each species exhibits a preferred ecological niche and host range, yet all share the capacity to breach superficial barriers under conducive conditions such as high humidity, compromised skin integrity, or prolonged exposure to contaminated habitats. Accurate identification of the mite type guides targeted acaricidal treatment and informs preventive measures, including environmental decontamination and personal protective practices.

Common Misconceptions

Subcutaneous ticks are often misunderstood, leading to incorrect assumptions about their origin and development.

Many believe that a single bite directly injects a tick beneath the skin. In reality, ticks embed in the epidermis or dermis during feeding; the subcutaneous appearance results from the tick’s body expanding as it swells with blood, not from an initial deep insertion.

Another prevalent myth holds that only certain tick species can penetrate below the surface. All hard‑bodied ticks are capable of producing a subcutaneous stage when they remain attached for extended periods, regardless of species.

A common misconception links subcutaneous ticks to poor personal hygiene. Tick attachment is independent of cleanliness; it depends on environmental exposure, host movement, and the tick’s questing behavior.

Some assert that immediate removal of a visible tick prevents subcutaneous development. Even prompt extraction may leave mouthparts embedded, which can later become encased by host tissue and appear subcutaneous.

Finally, many assume that subcutaneous ticks are a sign of severe infection. While they can transmit pathogens, their presence alone does not guarantee disease transmission; infection risk is determined by tick species, pathogen prevalence, and duration of attachment.

Correcting these misunderstandings helps focus preventive measures on habitat management, regular body checks, and proper tick removal techniques rather than on unfounded beliefs.

Factors Contributing to Subcutaneous Tick Infestations

Environmental Triggers

Exposure to Infested Animals

Exposure to animals harboring ticks creates a direct pathway for subcutaneous infestation. When a host animal carries attached or engorged ticks, close contact—such as grooming, feeding, or veterinary care—allows ticks to detach onto human skin. If removal is delayed, the parasite can penetrate deeper layers, resulting in a subcutaneous position.

Key mechanisms include:

Physical transfer: Ticks dislodge from fur or feathers during handling and crawl onto the person’s skin.
Embedding during attachment: While feeding on the animal, some ticks embed partially; subsequent contact can push the mouthparts into the human dermis.
Migration after removal: Incomplete extraction from the animal may leave portions of the tick’s mouthparts, which can be transferred to the handler and migrate inward.

Animals most frequently involved are livestock (cattle, sheep, goats), companion animals (dogs, cats) and wildlife (deer, rodents). Environments where these animals congregate—pastures, barns, shelters—heighten the risk of tick exposure. Prompt, thorough inspection of animals and immediate removal of attached ticks reduce the likelihood of subcutaneous penetration in humans.

Contaminated Environments

Contaminated environments create conditions that facilitate the penetration of ticks into the dermal layer. Soil enriched with organic waste, decaying vegetation, and animal droppings retains high humidity, which sustains tick activity and encourages questing behavior close to the ground. When humans or animals traverse such areas, ticks can latch onto hair or clothing and, under pressure from movement or grooming, migrate deeper into the skin.

Key factors in polluted habitats that increase subdermal tick incidents:

Accumulation of fecal matter and urine that raises microbial load, weakening skin barriers.
Persistent moisture from water runoff or irrigation, maintaining a microclimate favorable for tick survival.
Dense low-lying vegetation that shelters ticks and offers direct contact with the host’s skin.
Presence of reservoir hosts (rodents, birds) that shed infected ticks into the environment.

Mitigation measures focus on reducing environmental contamination:

Regular removal of animal waste from recreational and agricultural zones.
Implementation of drainage systems to prevent water stagnation.
Controlled mowing or clearing of understory vegetation in high‑traffic areas.
Application of environmentally safe acaricides in identified hotspots.

By addressing these ecological contributors, the likelihood of ticks embedding beneath the skin diminishes markedly.

Host Susceptibility

Weakened Immune System

A weakened immune system reduces the body’s ability to detect and eliminate tick larvae that have penetrated the dermis. Impaired cellular immunity slows the recruitment of macrophages and neutrophils to the bite site, allowing the arthropod to remain hidden beneath the skin.

Key mechanisms linking immune deficiency to subcutaneous tick development include:

Decreased production of inflammatory cytokines such as IL‑1, IL‑6, and TNF‑α, which normally signal tissue damage.
Lowered activity of natural killer cells that target ectoparasite antigens.
Impaired antibody-mediated opsonization, reducing the clearance of tick saliva proteins that modulate host defenses.
Chronic conditions (e.g., HIV, chemotherapy, autoimmune disease) that suppress both innate and adaptive responses, creating a permissive environment for larvae survival.

Consequently, individuals with compromised immunity experience higher rates of concealed tick infestations, prolonged attachment periods, and increased risk of secondary infections. Monitoring immune status and promptly treating any tick exposure are essential preventive measures.

Pre-existing Skin Conditions

Pre‑existing dermatoses create an environment that facilitates the migration of ticks into the subcutaneous layer. Disrupted epidermal integrity, chronic inflammation, and altered skin microbiota reduce the barrier function, allowing attached ticks to penetrate deeper tissues more readily.

Common conditions that increase susceptibility include:

Psoriasis: hyperkeratotic plaques and fissures provide entry points.
Atopic dermatitis: persistent scratching damages the stratum corneum, exposing underlying layers.
Lichen simplex chronicus: thickened, lichenified skin lowers resistance to tick attachment.
Chronic venous insufficiency: edema and skin breakdown weaken protective layers.
Diabetic foot ulcers: prolonged wounds and reduced healing capacity encourage deeper colonization.

These disorders often involve compromised immune responses at the cutaneous level. Cytokine imbalances and reduced antimicrobial peptide production diminish local defenses, permitting ticks to remain concealed beneath the skin. Management of underlying dermatologic disease—through topical corticosteroids, emollients, or systemic therapy—restores barrier integrity and reduces the risk of hidden tick infestations.

Lifecycle and Transmission

Stages of Development

Egg Stage

Subcutaneous tick infestations originate from eggs deposited by adult females on the host’s skin or in the surrounding environment. After attachment, females lay thousands of eggs that hatch into larvae capable of penetrating the dermis. The egg stage determines the timing and magnitude of the subsequent invasion.

Egg development requires specific temperature, humidity, and nutrient conditions. Optimal temperature ranges from 20 °C to 30 °C; relative humidity above 80 % prevents desiccation. Adequate blood meals from the host provide the protein reserves necessary for embryogenesis. Failure to meet these parameters results in reduced hatch rates and delayed larval emergence.

The hatch period typically lasts 5–10 days, after which larvae seek entry points such as hair follicles or microabrasions. Rapid hatching combined with high larval density increases the probability of dermal penetration, leading to the appearance of subcutaneous ticks. Consequently, environmental factors that accelerate egg maturation directly influence the frequency of hidden infestations.

Larval and Nymphal Stages

Ticks that become embedded beneath the skin typically do so during their early developmental phases. The larval and nymphal stages possess the physiological and behavioral characteristics that facilitate subcutaneous penetration, especially when environmental and host‑related conditions align.

Larvae are the smallest tick form, measuring 0.5–0.8 mm after hatching. Their mouthparts are proportionally short but capable of piercing thin epidermal layers. When a host’s skin is moist, warm, or mildly traumatized—such as during grooming, shaving, or exposure to insect repellent—larvae may detach before completing a superficial feed and continue migration into the dermis. The limited blood intake at this stage often leaves the tick partially engorged, increasing the likelihood of incomplete attachment and subdermal lodging.

Nymphs, larger than larvae (1.5–2 mm pre‑feed), exhibit stronger chelicerae and a greater capacity for blood acquisition. Their questing activity peaks in spring and early summer, coinciding with higher host activity. If a host’s skin barrier is compromised—by abrasion, eczema, or dense clothing—nymphs can penetrate deeper tissue while attempting to secure a prolonged feeding site. Their relatively longer feeding duration (several days) raises the probability of tissue invasion if the host’s immune response or grooming behavior disrupts the attachment before the tick fully engorges.

Factors that promote subcutaneous entry during these stages include:

Warm, humid microclimates that stimulate tick activity.
Host skin conditions that reduce epidermal integrity.
Rapid host movement or grooming that dislodges the tick before surface attachment is complete.
Use of repellents or chemicals that irritate the skin, encouraging deeper penetration as the tick seeks a stable feeding site.

Understanding the biological constraints of larvae and nymphs clarifies why subcutaneous ticks appear primarily during these early life stages. Effective prevention focuses on minimizing skin irritation, maintaining proper grooming practices, and reducing exposure to tick‑infested environments during peak larval and nymphal activity periods.

Adult Stage

Adult ticks represent the final developmental phase, characterized by larger body size, fully developed mouthparts, and the capacity to reproduce. At this stage, females ingest substantial blood volumes, often remaining attached for several days to complete engorgement.

Subcutaneous localization of adult ticks results from several physiological and ecological mechanisms. Deep insertion of the hypostome during attachment allows the parasite to penetrate beyond the epidermis. Prolonged feeding suppresses local inflammation, enabling the tick to remain concealed within the dermal or subdermal layers. Species with robust cement secretion create a stable anchor that resists host grooming and removal, further promoting hidden residence.

Factors that increase the likelihood of adult ticks appearing subcutaneously include:

Host skin thickness or dense hair coat that facilitates deeper penetration.
Tick species possessing strong cement glands (e.g., Dermacentor spp., Ixodes spp.).
Warm, humid environments that extend the feeding period.
Immunocompromised or immunologically tolerant hosts that exhibit reduced inflammatory response.
Repeated exposure to tick-infested habitats, leading to cumulative infestations.

Understanding these elements clarifies why adult ticks, rather than immature stages, are most often associated with subcutaneous presentations.

Modes of Transmission

Direct Contact

Direct contact with environments inhabited by ticks is a primary pathway for the development of subcutaneous infestations. When skin contacts vegetation, animal fur, or contaminated clothing, tick larvae or nymphs can attach and embed their mouthparts, eventually burrowing deeper into the dermal layers. The process begins with a tick sensing heat and carbon dioxide, prompting it to crawl onto the host’s surface. If the host’s skin is moist or has microabrasions, the tick can penetrate more readily and move into the subcutaneous tissue.

Key factors that increase the likelihood of subcutaneous entry through direct contact include:

Dense ground cover such as tall grass, leaf litter, or brush where ticks quest for hosts.
Contact with domestic or wild animals that carry ticks, especially during grooming or handling.
Wearing tight or synthetic garments that trap ticks against the skin, reducing the chance of removal.
Engaging in outdoor activities without protective clothing or repellents, which leaves skin exposed to tick habitats.

Preventive measures focus on minimizing direct exposure: use appropriate clothing barriers, conduct thorough skin checks after outdoor exposure, and apply approved acaricides to both skin and attire. Prompt removal of attached ticks before they embed reduces the risk of subcutaneous migration and associated complications.

Indirect Contact

Subcutaneous ticks develop when a tick attaches to a host, feeds briefly, and then migrates into the dermal layer. The migration often occurs without the host noticing the initial bite, allowing the arthropod to reside beneath the skin for several days.

Indirect contact contributes to this process by exposing hosts to ticks that have been transferred from contaminated objects or environments rather than through direct attachment on a living host. When a tick detaches from an animal or a person and lands on a surface, it can remain viable for hours. Subsequent contact with that surface provides an opportunity for the tick to attach to a new host and begin subdermal migration.

Typical sources of indirect exposure include:

Bedding, blankets, and clothing formerly worn by an infested animal or person
Furniture upholstery in homes or veterinary clinics where ticks have been present
Grooming tools, such as brushes and combs, that have contacted infested fur
Vehicles, especially pet carriers and car seats, after transport of a tick‑bearing animal

Preventive actions focus on minimizing the persistence of ticks on inanimate items. Regular laundering of textiles at high temperatures, thorough vacuuming of upholstered furniture, and disinfection of grooming equipment reduce the likelihood of indirect transmission. Inspecting and treating pets for ectoparasites before they enter indoor environments further limits the reservoir of ticks that could contaminate surfaces.

Symptoms and Diagnosis

Clinical Manifestations

Skin Lesions

Subcutaneous ticks develop beneath the skin after the parasite penetrates the epidermis and embeds its head in the dermal layer. The initial breach creates a localized skin lesion that often appears as a small, erythematous papule or a raised nodule. The lesion’s morphology reflects the tick’s feeding apparatus and the host’s inflammatory response.

The lesion progresses through distinct phases:

Early stage (24–48 hours): mild redness, slight swelling, occasional pruritus.
Mid stage (3–7 days): enlargement of the nodule, possible central ulceration, increased warmth.
Late stage (beyond 7 days): necrotic core, potential secondary bacterial infection, scar formation after removal.

Factors that promote lesion formation include:

Tick species with elongated mouthparts capable of deep tissue penetration.
Host skin thickness and elasticity, which influence the depth of insertion.
Ambient humidity and temperature, which affect tick activity and feeding duration.
Presence of pre‑existing dermal conditions that compromise barrier integrity.

Diagnosis relies on visual inspection of the characteristic nodule, palpation of a firm core, and, when necessary, dermatoscopic evaluation to identify the tick’s mouthparts. Imaging (ultrasound) may confirm subdermal location if the lesion is atypical.

Effective management involves:

Prompt removal of the tick with fine‑pointed forceps, grasping the mouthparts close to the skin surface to minimize tissue trauma.
Disinfection of the excision site with an antiseptic solution.
Monitoring for signs of infection (increased pain, purulent discharge) and initiating appropriate antibiotics if bacterial colonization occurs.
Follow‑up examination to ensure complete resolution and to assess for potential tick‑borne pathogen transmission.

Understanding the pathophysiology of these skin lesions clarifies why subcutaneous ticks emerge and guides clinicians in early detection and treatment.

Itching and Irritation

Subcutaneous ticks embed beneath the skin surface, releasing saliva that contains anticoagulants, enzymes, and antigenic proteins. These substances trigger a localized inflammatory response, producing histamine release that manifests as itching and irritation. The reaction intensity varies with tick species, feeding duration, and individual sensitivity; some hosts develop pronounced erythema and edema, while others experience only mild discomfort.

Key mechanisms producing the sensation include:

Histamine-mediated vasodilation, causing pruritus and swelling.
Proteolytic enzymes degrading tissue, exposing nerve endings.
Immunoglobulin E (IgE) sensitization leading to allergic-type reactions.
Secondary bacterial colonization that amplifies inflammation.

Effective management requires prompt removal of the tick, cleansing the area with antiseptic, and application of topical corticosteroids or antihistamines to reduce itching. Persistent or spreading symptoms warrant medical evaluation for possible tick-borne infections. Prevention strategies focus on protective clothing, regular skin inspections after outdoor exposure, and environmental control of tick habitats.

Secondary Infections

Subcutaneous ticks embed beneath the skin, creating a portal for opportunistic microorganisms. The bite disrupts the epidermal barrier, introduces tick‑borne flora, and provides a moist environment that favors bacterial proliferation.

Common secondary infections include:

Staphylococcus aureus cellulitis – characterized by redness, swelling, and pain.
Streptococcus pyogenes erysipelas – presents with sharply demarcated erythema and fever.
Borrelia burgdorferi Lyme disease – may develop weeks after the initial bite, with joint pain and neurological signs.
Rickettsia spp. spotted fever – manifests as fever, rash, and headache.

Pathogenesis involves direct inoculation of skin flora during tick attachment, toxin‑mediated tissue damage that impairs local immunity, and secondary colonization by environmental bacteria. Host factors such as compromised immunity, diabetes, or chronic skin conditions increase susceptibility. Delayed removal of the tick prolongs exposure to salivary secretions that contain immunosuppressive compounds, further elevating infection risk.

Effective management requires prompt tick extraction, thorough wound cleansing with antiseptic solution, and empirical antibiotic therapy targeting gram‑positive cocci and, when indicated, tick‑borne pathogens. Follow‑up examinations should assess for signs of systemic involvement, and patients with high‑risk comorbidities may benefit from prophylactic doxycycline or clindamycin, depending on regional pathogen prevalence.

Diagnostic Methods

Skin Scraping

Skin scraping is a diagnostic technique that directly samples the epidermal layer and superficial dermis. By collecting a thin fragment of skin, clinicians obtain material suitable for microscopic examination, culture, or molecular analysis. This approach reveals the presence of embedded arthropods, their eggs, or associated inflammatory responses that may explain the development of subcutaneous tick lesions.

The procedure involves the following steps:

Clean the target area with antiseptic solution.
Apply a sterile scalpel or dermal curette to the lesion, exerting gentle pressure to obtain a thin slice of skin.
Transfer the specimen to a glass slide, add appropriate staining reagents, and cover with a coverslip.
Examine the slide under high‑magnification optics to identify tick parts, surrounding tissue reaction, and possible secondary pathogens.

Findings from skin scraping can clarify several mechanisms underlying subdermal tick occurrence:

Direct implantation of tick mouthparts during feeding, leading to tissue migration.
Host immune response that encapsulates the parasite, creating a palpable nodule.
Secondary bacterial infection that exacerbates tissue swelling and mimics tick presence.

Accurate interpretation of scraped samples guides targeted therapy, such as surgical removal, antimicrobial treatment, or preventive measures to reduce future infestations.

Biopsy

Biopsy provides direct tissue evidence when investigating the origin of subdermal tick lesions. By extracting a small sample from the affected area, histopathology can reveal inflammatory patterns, necrosis, or the presence of tick salivary components that differentiate primary infestations from secondary infections.

Microscopic examination identifies:

Tick mouthparts embedded in the dermis or hypodermis
Host immune response, including eosinophilic infiltrates and granuloma formation
Secondary bacterial colonization, such as Staphylococcus or Streptococcus species

Molecular techniques applied to biopsy material, such as PCR, detect tick‑borne pathogens (e.g., Borrelia, Rickettsia) that may trigger deeper tissue involvement. Positive results clarify whether systemic infection drives the subcutaneous presentation, guiding targeted antimicrobial therapy.

When clinical assessment suggests atypical tick behavior—such as migration beneath the skin—biopsy distinguishes genuine tick embedment from mimicking conditions like cysts or foreign‑body granulomas. Accurate diagnosis prevents unnecessary surgical excision and informs preventive measures, including habitat management and personal protective strategies.

Prevention and Management Strategies

Preventive Measures

Personal Hygiene

Personal hygiene directly influences the likelihood of subcutaneous tick attachment. Regular removal of debris, sweat, and moisture from the skin creates an environment less attractive to questing ticks, which seek humid, warm surfaces for anchorage. Clean, dry skin also reduces the presence of bacterial colonies that emit odors drawing arthropods.

Effective hygiene measures include:

Daily showers with thorough cleaning of exposed areas, especially legs, ankles, and groin.
Prompt drying of skin after bathing, swimming, or heavy perspiration.
Use of antiseptic soaps or wipes on regions frequently contacted by vegetation.
Routine inspection of clothing and body for attached arthropods after outdoor activities.
Immediate laundering of garments worn in tick‑infested habitats at high temperatures.

Adhering to these practices diminishes the conditions that facilitate tick penetration beneath the epidermis, thereby lowering the incidence of subcutaneous infestations.

Pet Care

Subcutaneous tick infestations in pets arise when adult female ticks embed their bodies beneath the skin to feed and lay eggs. The primary drivers are:

Contact with tick‑infested vegetation or wildlife habitats.
Inadequate use of preventive acaricides on the animal’s coat.
Seasonal peaks in tick activity, especially in spring and early summer.
Poor grooming practices that leave dense fur unchecked.

Environmental conditions that favor tick development—warm temperatures, high humidity, and abundant leaf litter—increase the likelihood of pets acquiring hidden ticks. Animals with thick or long hair provide a protective niche, allowing ticks to remain unnoticed while they burrow. Skin injuries, such as scratches or wounds, create entry points that facilitate deeper penetration.

Effective pet care measures include regular inspection of the entire body, focusing on areas where ticks hide, such as between the shoulder blades, under the tail, and around the ears. Applying veterinarian‑approved tick preventatives according to the recommended schedule reduces the chance of subdermal colonization. Maintaining a clean, tick‑free environment by trimming grass, removing leaf litter, and treating the yard with appropriate acaricides further limits exposure.

If a subcutaneous tick is detected, immediate veterinary intervention is required. Proper removal involves surgical extraction to avoid incomplete detachment, which can cause inflammation or secondary infection. Post‑removal monitoring for signs of tick‑borne disease—fever, lethargy, loss of appetite—ensures timely treatment.

Environmental Control

Environmental control reduces the incidence of subcutaneous tick infestations by limiting the habitats where ticks develop and by disrupting their life cycle. Maintaining low humidity and eliminating dense ground cover prevent the micro‑climate conditions that favor egg laying and larval survival. Regular mowing of lawns, removal of leaf litter, and clearing of tall grasses diminish shelter sites, thereby decreasing the likelihood that ticks will migrate into animal skin.

Effective practices include:

Trimming vegetation to a height of no more than 4 inches.
Removing leaf piles, brush, and debris from perimeters.
Applying acaricides to high‑risk zones following label instructions.
Installing physical barriers, such as fine‑mesh fencing, around animal enclosures.
Ensuring proper drainage to avoid water accumulation that raises humidity.

Implementing these measures creates an environment hostile to tick development, directly lowering the risk of subcutaneous intrusion. Continuous monitoring and prompt remediation of emerging habitats sustain long‑term protection.

Treatment Options

Topical Medications

Topical agents can modify the skin environment in ways that affect the likelihood of ticks embedding beneath the epidermis. Potent corticosteroid ointments, calcineurin‑inhibitor creams, and other immunosuppressive preparations diminish local immune responses, impairing the skin’s ability to reject arthropod attachment. Repeated application of these products may thin the stratum corneum, creating micro‑abrasions that facilitate tick penetration.

High‑potency corticosteroid creams (e.g., clobetasol propionate)
Topical tacrolimus or pimecrolimus formulations
Long‑term use of antifungal creams containing azoles, which can disrupt normal flora

Conversely, approved tick‑repellent topicals provide a chemical barrier that deters attachment and reduces the incidence of subcutaneous migration. These formulations contain active ingredients that interfere with tick sensory mechanisms or create an unfavorable surface for questing.

Permethrin‑based lotions (0.5 %–1 % concentration)
DEET‑containing sprays applied to skin (up to 30 % concentration)
IR3535 or picaridin formulations approved for dermal use

The underlying mechanisms involve altered skin chemistry, changes in odor profiles, and compromised barrier integrity. Immunosuppressive agents lower cytokine production and reduce inflammatory signaling, which normally alerts the host to arthropod intrusion. Barrier‑disrupting compounds expose deeper dermal layers, granting ticks easier access to subcutaneous tissue.

Clinical practice should prioritize assessment of topical regimens in patients living in tick‑prevalent regions. When immunosuppressive creams are necessary, limit duration and potency, and supplement with an appropriate repellent. Regular skin examinations can detect early tick ingress, allowing prompt removal and reducing the risk of secondary infection.

Oral Medications

Oral medications can contribute to the development of subcutaneous tick lesions by altering host defenses, affecting skin integrity, or modifying blood composition. Immunosuppressive drugs, such as corticosteroids and biologic agents (e.g., TNF‑α inhibitors), reduce the immune response, allowing ticks to embed more deeply without eliciting immediate inflammation. Anticoagulants, including warfarin and direct oral anticoagulants, increase bleeding in the attachment site, facilitating tick survival under the skin. Certain antihistamines and anticholinergic agents diminish itching and pain perception, delaying detection and removal.

Key oral agents associated with increased risk:

Corticosteroids (prednisone, methylprednisolone)
Biologic immunomodulators (adalimumab, etanercept)
Conventional immunosuppressants (methotrexate, azathioprine)
Anticoagulants (warfarin, apixaban, rivaroxaban)
Antihistamines (cetirizine, loratadine)
Anticholinergics (diphenhydramine, scopolamine)

Patients receiving these medications should monitor skin for atypical nodules, especially after outdoor exposure, and seek prompt evaluation. Early identification reduces the likelihood of complications such as secondary infection or systemic tick‑borne disease.