Which pill should be chosen after a tick bite?

Understanding Tick-Borne Diseases

Common Tick-Borne Infections

Lyme Disease (Borreliosis)

Lyme disease, caused by the bacterium Borrelia burgdorferi, is the most common tick‑borne infection in temperate regions. Early manifestations include erythema migrans, flu‑like symptoms, and occasionally neurologic or cardiac involvement. Prompt antimicrobial therapy reduces the risk of disseminated disease and long‑term complications.

Evidence‑based guidelines recommend oral doxycycline as the first‑line agent for most adults and children over eight years old, provided there are no contraindications. Alternative regimens apply when doxycycline cannot be used.

Doxycycline 100 mg twice daily for 10–21 days (adults)
Doxycycline 4.4 mg/kg twice daily for 10–21 days (children > 8 years)
Amoxicillin 500 mg three times daily for 14–21 days (pregnant patients, children < 8 years)
Cefuroxime axetil 500 mg twice daily for 14–21 days (alternative when doxycycline is unsuitable)

Selection criteria include patient age, pregnancy status, allergy profile, severity of presentation, and potential drug interactions. Doxycycline offers superior tissue penetration, covers atypical manifestations, and shortens treatment duration, making it the preferred choice for uncomplicated early Lyme disease. Amoxicillin and cefuroxime serve as safe alternatives when doxycycline is contraindicated. Intravenous ceftriaxone is reserved for severe neurologic or cardiac involvement, not for routine post‑bite prophylaxis.

Tick-Borne Encephalitis (TBE)

Tick‑borne encephalitis (TBE) is a viral infection transmitted by the bite of infected Ixodes ticks. The disease may develop after a latency period of 7‑14 days and can progress from a mild febrile phase to meningitis, encephalitis, or meningo‑encephalitis. Diagnosis relies on clinical presentation, epidemiologic exposure, and detection of TBE‑specific IgM antibodies in serum or cerebrospinal fluid.

There is no approved antiviral medication specifically indicated for TBE. Management therefore focuses on:

Immediate observation for neurologic signs during the incubation window.
Symptomatic treatment with antipyretics (paracetamol or ibuprofen) and analgesics.
Hospital admission for patients with severe headache, fever, or focal neurologic deficits.
Supportive care, including hydration, respiratory support, and seizure control when required.
Consideration of corticosteroids only in selected cases of severe cerebral edema, under specialist supervision.

Pre‑exposure vaccination remains the only proven preventive measure. For individuals without prior immunization, a rapid‑schedule vaccine series may be initiated after exposure, but it does not replace the need for clinical monitoring. Consequently, no specific pill can be prescribed solely on the basis of a tick bite; the appropriate course is vigilant observation and supportive therapy, with vaccination as the primary prophylactic strategy.

Anaplasmosis

Anaplasmosis is a bacterial infection transmitted by the bite of infected Ixodes ticks. The pathogen, Anaplasma phagocytophilum, invades neutrophils and causes systemic inflammation. Typical manifestations appear 1–2 weeks after exposure and include fever, chills, headache, myalgia, and leukopenia. Laboratory findings often reveal elevated liver enzymes and mild thrombocytopenia. Early recognition prevents progression to severe complications such as respiratory distress, cardiac involvement, or organ failure.

Diagnosis relies on a combination of clinical assessment, exposure history, and laboratory testing. Polymerase chain reaction (PCR) of whole blood provides rapid confirmation, while serologic testing (IgG/IgM) supports retrospective diagnosis. Peripheral blood smears may show intracytoplasmic morulae in neutrophils, but sensitivity is limited.

First‑line therapy is doxycycline, administered orally at 100 mg twice daily for 10–14 days. Doxycycline achieves bactericidal concentrations in intracellular compartments and reduces symptom duration when started promptly. Alternatives include:

Minocycline 100 mg twice daily (used when doxycycline is contraindicated).
Rifampin 600 mg once daily (reserved for patients unable to tolerate tetracyclines).

Pregnant or lactating individuals should avoid tetracyclines; rifampin is the preferred option in these cases, though data on efficacy are limited. Severe disease may require intravenous doxycycline 100 mg every 12 hours.

Monitoring includes daily assessment of fever, white‑blood‑cell count, and liver enzymes. Resolution of symptoms typically occurs within 48 hours of initiating doxycycline. Persistent fever beyond 72 hours warrants reassessment for co‑infection (e.g., Borrelia burgdorferi or Babesia microti) and possible adjustment of antimicrobial regimen.

In summary, after a tick bite with suspected Anaplasmosis, the recommended oral agent is doxycycline 100 mg twice daily for a minimum of 10 days, with minocycline or rifampin as secondary choices when contraindications exist. Prompt treatment shortens illness and prevents serious complications.

Ehrlichiosis

Ehrlichiosis is a bacterial infection transmitted by ticks, primarily caused by Ehrlichia chaffeensis in the United States. The pathogen invades white‑blood cells, leading to fever, headache, muscle pain, and laboratory abnormalities such as leukopenia and thrombocytopenia. Prompt antimicrobial therapy reduces the risk of severe complications, including respiratory failure, meningoencephalitis, and death.

The drug of choice for adults and children over eight years of age is doxycycline, administered at 100 mg orally twice daily for 7–14 days. Doxycycline’s intracellular penetration and activity against Ehrlichia species make it the most effective option. For patients who cannot tolerate tetracyclines, alternative regimens include:

Rifampin 300 mg orally twice daily for 7–10 days.
Chloramphenicol 500 mg intravenously every 6 hours (reserved for severe cases where doxycycline is contraindicated).

Pregnant or lactating women require special consideration; doxycycline is generally avoided, and consultation with an infectious‑disease specialist is advised to determine the safest alternative.

Early treatment, preferably initiated within 24–48 hours of symptom onset, correlates with rapid clinical improvement and normalization of laboratory values. Delay beyond five days increases the likelihood of prolonged fever and organ dysfunction.

In summary, after a tick bite that raises suspicion for ehrlichiosis, doxycycline should be selected as the first‑line oral therapy, with rifampin or chloramphenicol reserved for specific contraindications. Immediate administration optimizes outcomes and minimizes the potential for severe disease.

Babesiosis

Babesiosis is a tick‑borne infection caused by intra‑erythrocytic parasites of the genus Babesia. After a tick bite, the decision on antimicrobial therapy depends on the likelihood of babesiosis, patient risk factors, and disease severity.

If clinical suspicion is high—fever, hemolytic anemia, or recent exposure in an endemic area—empiric treatment should begin promptly while awaiting laboratory confirmation (blood smear or PCR). The standard regimens are:

Atovaquone + Azithromycin: 750 mg atovaquone twice daily with 500–1000 mg azithromycin on day 1, then 250 mg atovaquone twice daily with 500 mg azithromycin daily for 7–10 days. Preferred for mild to moderate disease and for patients without severe hemolysis.
Clindamycin + Quinine: 600 mg clindamycin every 6 h plus 650 mg quinine three times daily for 7–10 days. Reserved for severe infection, high parasitemia (>10 %), or immunocompromised hosts; requires monitoring for quinine‑related cardiotoxicity and clindamycin‑associated colitis.

Additional considerations:

Pregnant or lactating women: azithromycin alone may be used, acknowledging reduced efficacy.
Renal or hepatic impairment: dose adjustments for atovaquone and quinine are necessary.
Co‑infection with Lyme disease or anaplasmosis: doxycycline is added to cover the additional pathogens.

Therapeutic success is assessed by repeat blood smears at days 7 and 14; persistence of parasites warrants extended treatment or switch to the alternative regimen. Early, appropriate drug selection after a tick bite reduces the risk of complications such as acute respiratory distress syndrome, renal failure, or persistent anemia.

Risk Factors and Geographic Distribution

When a tick bite raises concern for Lyme disease, the decision to prescribe doxycycline, amoxicillin, or cefuroxime hinges on the patient’s exposure profile. Two critical determinants are the prevalence of Borrelia‑infecting ticks in the region and the individual’s susceptibility to adverse drug reactions.

Risk factors that increase the likelihood of infection include:

Residence or recent travel to areas where Ixodes scapularis or Ixodes ricinus are endemic.
Outdoor activities in wooded or grassy habitats during the peak tick season (April–October in the Northern Hemisphere).
Prolonged attachment of the tick, especially beyond 24 hours.
Age under 8 years or over 65 years, which may affect drug metabolism.
Known allergy to tetracyclines, penicillins, or cephalosporins, limiting therapeutic options.

Geographic distribution of Borrelia‑carrying ticks is uneven. In North America, high incidence zones span the Northeastern United States, the Upper Midwest, and parts of the Pacific Northwest. In Europe, endemic regions include the Baltic states, Scandinavia, and central countries such as Germany and Austria. In Asia, documented foci exist in parts of Russia, Japan, and China. Areas with low tick density or where other tick‑borne pathogens predominate (e.g., Rocky Mountain spotted fever in the Southwest United States) may warrant alternative prophylaxis.

The choice of medication therefore aligns with the regional pathogen profile and the patient’s risk spectrum. Doxycycline is preferred in most endemic zones for adults without contraindications, owing to its efficacy against early disseminated infection and its convenient dosing. Amoxicillin serves as the first‑line alternative for children, pregnant women, or individuals intolerant of doxycycline. Cefuroxime offers a secondary option when both doxycycline and amoxicillin are unsuitable. Accurate assessment of exposure location and personal health factors ensures the selected pill addresses the most probable infectious threat.

First Steps After a Tick Bite

Proper Tick Removal Techniques

Effective removal of a tick is a prerequisite for any subsequent therapeutic decision after an encounter with the parasite. The process must minimize the risk of pathogen transmission and avoid leaving mouthparts embedded in the skin.

Use fine‑point tweezers or a specialized tick‑removal tool; avoid blunt instruments.
Grasp the tick as close to the skin surface as possible, securing the head and mouthparts without squeezing the body.
Apply steady, downward pressure to pull the tick straight out; do not twist or jerk, which can cause mouthparts to break off.
After extraction, inspect the bite site for any remaining fragments; if present, repeat the procedure with clean tweezers.
Disinfect the area with an antiseptic solution such as povidone‑iodine or alcohol.
Place the tick in a sealed container with a label indicating date and location of attachment; retain for potential laboratory analysis.

Following removal, monitor the bite site for signs of erythema, expanding rash, or flu‑like symptoms. Document the date of removal, as the incubation period for tick‑borne diseases dictates the timing of prophylactic medication. If any adverse signs develop within the typical incubation window, initiate the appropriate antimicrobial regimen as prescribed by a healthcare professional.

When to Seek Medical Attention

A tick bite may transmit pathogens that require prompt evaluation. Seek professional care if any of the following conditions appear:

Redness or swelling extending beyond the bite site
A rash resembling a bull’s‑eye pattern
Fever, chills, headache, or muscle aches within weeks of the bite
Persistent fatigue or joint pain
Neurological symptoms such as numbness, tingling, or facial weakness
Any known allergy to the recommended antimicrobial agents

Medical assessment should occur within 24 hours of symptom onset. The clinician will confirm diagnosis, determine the appropriate antimicrobial regimen, and advise on follow‑up. Delayed treatment increases the risk of complications, including chronic joint inflammation or neurological impairment. If uncertainty exists about the bite’s timing or exposure risk, contact a healthcare provider without hesitation.

The Importance of Prompt Action

A tick bite can transmit bacteria or viruses within hours. Immediate measures limit pathogen transfer and lower the chance of disease development.

Delaying treatment increases the likelihood that the organism establishes infection, which can lead to more severe symptoms, longer therapy, and higher complication rates.

Prompt action consists of three decisive steps:

Remove the tick promptly using fine‑tipped tweezers, grasping close to the skin and pulling steadily.
Clean the bite area with antiseptic and document the time of removal.
Contact a healthcare professional without delay; if local guidelines recommend prophylaxis, begin the prescribed medication as soon as possible.

The speed of these actions directly influences therapeutic success and reduces the risk of long‑term health effects.

Pharmacological Interventions and Prevention

Post-Exposure Prophylaxis (PEP) for Lyme Disease

Doxycycline Regimens

A tick bite can introduce bacterial pathogens that require prompt antimicrobial therapy. Doxycycline is the preferred agent for both prophylaxis and early treatment of tick‑borne infections because of its activity against Borrelia burgdorferi, Anaplasma phagocytophilum and Ehrlichia chaffeensis.

For single‑dose prophylaxis, a 200 mg oral tablet should be taken within 72 hours of the bite. In children weighing less than 45 kg, a weight‑adjusted dose of 4 mg/kg (maximum 200 mg) is recommended. This regimen reduces the risk of Lyme disease when the tick is identified as Ixodes species and the exposure is considered high.

When early Lyme disease is diagnosed, the standard therapeutic course consists of 100 mg doxycycline taken twice daily for 14–21 days. Pediatric dosing follows 4.4 mg/kg per dose (maximum 100 mg) twice daily, adjusted for weight. For anaplasmosis or ehrlichiosis, the same dosage and duration apply, with treatment extending to 10–14 days for uncomplicated cases.

Key points for safe use:

Avoid in pregnant or lactating women; alternative agents required.
Discontinue if severe photosensitivity or allergic reaction occurs.
Monitor liver function in patients with hepatic impairment.
Counsel patients to take the medication with a full glass of water and remain upright for at least 30 minutes to reduce esophageal irritation.

These regimens provide evidence‑based guidance for selecting doxycycline after a tick exposure, balancing efficacy with safety considerations.

Contraindications and Side Effects

After a tick bite, prophylactic antibiotics are prescribed to prevent Lyme disease. The two most frequently used agents are doxycycline and amoxicillin; cefuroxime axetil and azithromycin are alternatives. Understanding contraindications and adverse reactions is essential for safe selection.

Doxycycline

Contraindications: pregnancy, lactation, known hypersensitivity to tetracyclines, severe hepatic impairment, children younger than eight years.
Common adverse effects: gastrointestinal irritation, nausea, vomiting, photosensitivity, esophageal ulceration if not taken with sufficient water.
Less frequent but serious reactions: intracranial hypertension, severe allergic rash, hepatic toxicity.

Amoxicillin

Contraindications: documented allergy to penicillins or cephalosporins, severe renal dysfunction without dose adjustment, mononucleosis (risk of rash).
Common adverse effects: diarrhea, nausea, abdominal pain, rash, candidiasis.
Rare severe events: anaphylaxis, Stevens‑Johnson syndrome, hemolytic anemia.

Cefuroxime axetil

Contraindications: penicillin allergy (cross‑reactivity possible), severe renal insufficiency without dose reduction.
Common adverse effects: dyspepsia, flatulence, rash, dizziness.
Rare severe reactions: anaphylactic shock, Clostridioides difficile colitis, thrombocytopenia.

Azithromycin

Contraindications: known macrolide hypersensitivity, severe hepatic disease, concurrent use of drugs that prolong QT interval.
Common adverse effects: abdominal discomfort, diarrhea, nausea, taste disturbance.
Rare severe events: QT prolongation leading to arrhythmia, hepatotoxicity, severe allergic reactions.

Selection must consider patient age, pregnancy status, renal and hepatic function, and any history of drug allergy. Monitoring for gastrointestinal upset, skin reactions, and neurologic symptoms during therapy reduces the risk of complications.

Medications for Tick-Borne Encephalitis

Vaccination as a Primary Prevention Strategy

Tick exposure carries a measurable risk of infection; immediate pharmacologic treatment is one response, yet immunization provides a pre‑exposure barrier.

Tick‑borne encephalitis (TBE) vaccine: three‑dose primary series followed by boosters every 3–5 years; efficacy exceeds 95 % in endemic regions.
Lyme disease vaccine (e.g., VLA15 in late‑stage trials): schedule includes two initial doses spaced one month apart, with a third dose after six months; early data indicate protection above 80 % against multiple Borrelia species.
Other tick‑transmitted pathogens lack licensed vaccines; prevention relies on avoidance measures and prompt therapy.

Immunization reduces the probability that a bite will progress to disease, thereby limiting the need for post‑exposure antibiotics. Population groups with high occupational or recreational exposure—foresters, hikers, military personnel—receive priority recommendations.

When vaccination is unavailable or incomplete, selection of an oral antimicrobial depends on local pathogen prevalence, timing of the bite, and patient risk factors; doxycycline remains the standard for early Lyme prophylaxis, while azithromycin or cefuroxime serve as alternatives in specific contexts.

Overall, primary prevention through vaccination shifts the management paradigm from reactive medication choice to proactive immunity, decreasing reliance on post‑bite drug regimens.

Symptomatic Treatment Options

After a tick attachment, immediate care focuses on preventing infection and relieving discomfort. Symptomatic treatment addresses pain, inflammation, itching, and fever while awaiting definitive diagnosis.

Analgesics: Acetaminophen or ibuprofen reduce headache, muscle aches, and localized pain. Ibuprofen also provides anti‑inflammatory effects.
Antihistamines: Oral cetirizine or diphenhydramine lessen itching and cutaneous reactions. Non‑sedating options are preferred for daytime use.
Topical steroids: Low‑potency hydrocortisone cream applied to erythema or rash controls local inflammation without systemic exposure.
Antipyretics: Acetaminophen or ibuprofen lower elevated body temperature; dosing follows standard adult or pediatric guidelines.
Wound care: Gentle cleansing with soap and water, followed by a sterile dressing, prevents secondary bacterial infection. If signs of bacterial involvement appear, a short course of oral antibiotics (e.g., amoxicillin‑clavulanate) may be indicated.

Monitoring for the emergence of a characteristic expanding rash, flu‑like symptoms, or neurological signs is crucial. If such manifestations develop, empirical doxycycline therapy is recommended pending laboratory confirmation.

Addressing Other Tick-Borne Infections

Antibiotic Choices for Anaplasmosis and Ehrlichiosis

After a tick bite, the most likely bacterial threats include Anaplasma phagocytophilum and Ehrlichia species. Prompt antimicrobial therapy reduces the risk of severe systemic illness.

Doxycycline remains the drug of choice for both infections. The standard adult regimen is 100 mg orally twice daily for 10–14 days. In children weighing at least 15 kg, the same dose applies. For infants and pregnant patients, doxycycline is contraindicated; alternatives include:

Azithromycin 500 mg on day 1, then 250 mg daily for 4 days (adult) or weight‑adjusted dosing in children.
Rifampin 600 mg daily (adult) or 10 mg/kg (pediatric) for 10–14 days, reserved for severe doxycycline intolerance.
Chloramphenicol 500 mg intravenously every 6 hours, limited to cases where other agents are unavailable.

When doxycycline is tolerated, its rapid bactericidal activity and excellent intracellular penetration make it superior to macrolides or rifampin. Treatment should begin as soon as clinical suspicion arises, even before laboratory confirmation, because delayed therapy correlates with higher rates of complications such as respiratory failure, renal impairment, or hemorrhagic manifestations. Monitoring of liver enzymes and complete blood counts is advisable during the course, particularly when using chloramphenicol or rifampin.

Treatment for Babesiosis

Babesiosis requires prompt antimicrobial therapy to eradicate the parasite and prevent severe hemolysis. The first‑line regimen combines atovaquone with azithromycin; this combination offers high efficacy with a favorable safety profile. Typical dosing is atovaquone 750 mg orally every 12 hours and azithromycin 500–1000 mg on day 1, then 250 mg daily, for a total of 7–10 days. Adjustments are necessary for patients with hepatic impairment or those receiving interacting drugs.

When parasitemia exceeds 10 % or the patient exhibits severe disease, the preferred alternative is clindamycin plus quinine. Standard dosing includes clindamycin 600 mg intravenously or orally every 6 hours and quinine 650 mg orally every 8 hours, administered for 7–10 days. Monitoring of cardiac rhythm and glucose levels is essential due to quinine’s cardiotoxic and hypoglycemic risks.

Key considerations for treatment selection:

Parasite load (low vs. high)
Clinical severity (mild, moderate, severe)
Patient comorbidities (liver, kidney, cardiac conditions)
Potential drug interactions (e.g., with warfarin, antiretrovirals)
Ability to tolerate oral versus intravenous administration

Follow‑up blood smears on days 3, 7, and 14 confirm clearance. Persistent positivity warrants extending therapy or switching to the clindamycin‑quinine regimen.

Misconceptions About Post-Bite Medications

Tick bites raise immediate concerns about infection risk, yet many patients accept incorrect medication advice. The most common error is the belief that a single dose of any antibiotic prevents Lyme disease. Only doxycycline, administered within 72 hours of removal, has proven efficacy for early prophylaxis; other antibiotics lack sufficient evidence and may foster resistance.

Another widespread myth claims that over-the-counter antihistamines eliminate the need for professional evaluation. Antihistamines relieve itching but do not address bacterial transmission. Prompt medical assessment remains essential to determine whether prophylactic treatment or watchful waiting is appropriate.

A third misconception suggests that a negative initial test excludes future disease. Serologic testing often yields false‑negative results during early infection; clinicians rely on clinical judgment and exposure history rather than a single laboratory value.

Correct practice involves:

Immediate removal of the tick with fine‑tipped tweezers.
Assessment of attachment duration (≥ 24 hours increases risk).
Consideration of doxycycline prophylaxis when criteria are met.
Follow‑up monitoring for erythema migrans or systemic symptoms for at least 30 days.

Considerations for Specific Populations

Children and Tick Bites

Tick bites in children require prompt assessment to determine whether antimicrobial prophylaxis is warranted. Decision hinges on attachment time exceeding 36 hours, exposure in areas where Ixodes species transmit Borrelia burgdorferi, and absence of immediate allergic reactions.

When prophylaxis is indicated, the first‑line agent for children eight years and older is doxycycline, administered as a single 200 mg dose (approximately 4 mg/kg, not exceeding 200 mg). For children younger than eight, doxycycline is contraindicated; alternatives include amoxicillin 50 mg/kg as a single dose, not exceeding 1 g, or cefuroxime axetil 30 mg/kg as a single dose, not exceeding 1 g. Choice among these agents depends on local resistance patterns and individual allergy history.

Key safety considerations: doxycycline may cause photosensitivity; parents should advise sun protection for 24 hours post‑dose. Amoxicillin and cefuroxime are generally well tolerated, but gastrointestinal upset may occur. Any history of severe penicillin allergy eliminates amoxicillin, directing therapy toward cefuroxime.

Following medication, caregivers must monitor the bite site for expanding erythema, fever, headache, or joint pain. Persistent or worsening symptoms require immediate medical evaluation, as they may indicate early Lyme disease or other tick‑borne infections.

Doxycycline (≥8 y): 200 mg single dose, 4 mg/kg max 200 mg
Amoxicillin (<8 y, no penicillin allergy): 50 mg/kg single dose, max 1 g
Cefuroxime axetil (<8 y, penicillin allergy): 30 mg/kg single dose, max 1 g

Appropriate selection, correct dosing, and vigilant observation together reduce the risk of infection while minimizing adverse effects in pediatric patients.

Pregnant and Breastfeeding Individuals

After a tick bite, prophylactic antibiotics may be indicated for individuals who are pregnant or nursing. Drug selection must prioritize fetal and infant safety while providing effective coverage against early Lyme disease.

Doxycycline, the standard choice for most adults, is contraindicated during pregnancy and lactation because of documented teratogenic risk and potential adverse effects on infant bone and tooth development.

Amoxicillin 200 mg taken orally twice daily for ten days is the preferred alternative. Clinical evidence supports its efficacy for early infection, and it is classified as safe for both gestation and breastfeeding.

Cefuroxime axetil 250 mg taken orally twice daily for ten days serves as a second‑line option when amoxicillin cannot be used. The drug’s safety profile during pregnancy and lactation is acceptable, with limited milk transfer.

Azithromycin may be employed for patients with a penicillin allergy. The regimen consists of 500 mg on the first day followed by 250 mg daily for four additional days. Available data indicate no significant risk to the fetus or nursing infant.

Key points for pregnant and breastfeeding patients:

Avoid doxycycline entirely.
Use amoxicillin as first‑line therapy.
Consider cefuroxime if amoxicillin intolerance occurs.
Reserve azithromycin for penicillin‑allergic cases.

All recommended agents have low concentrations in breast milk that are not clinically relevant. Initiation of therapy should occur within 72 hours of the bite and be confirmed by a healthcare professional who can assess contraindications and monitor response.

Individuals with Compromised Immune Systems

Immunocompromised patients face a higher probability of severe infection after a tick bite, making prompt antimicrobial prophylaxis essential.

The preferred agent is a single oral dose of doxycycline 200 mg taken within 72 hours of exposure. Doxycycline provides reliable coverage against Borrelia burgdorferi and is the only medication demonstrated to reduce the incidence of early Lyme disease in this population when administered promptly.

When doxycycline is contraindicated—due to allergy, pregnancy, or severe renal impairment—amoxicillin serves as the alternative. The recommended regimen is amoxicillin 2 g per day, divided into two doses, for 20 days, initiated as soon as possible after the bite. Azithromycin may be used only when both doxycycline and amoxicillin are unavailable; its efficacy is lower and the standard course is 500 mg on day 1 followed by 250 mg daily for four additional days.

If symptoms of Lyme disease develop despite prophylaxis, a 14‑ to 21‑day course of oral doxycycline (or amoxicillin if doxycycline remains unsuitable) should be started. For disseminated disease or neurologic involvement, intravenous ceftriaxone 2 g daily for 14‑28 days is indicated.

In summary, the optimal choice for immunocompromised individuals after a tick bite is a single dose of doxycycline, provided no contraindications exist; otherwise, a full 20‑day course of amoxicillin is the recommended alternative. Close clinical monitoring is required to detect early signs of infection and adjust therapy accordingly.