Why does the head itch after lice, and how to treat it?

Why does the head itch after lice, and how to treat it? - briefly

The scalp itches because the body reacts to lice saliva and the mechanical irritation from the insects and their eggs. Effective management includes a pediculicide treatment combined with meticulous nit‑combing and laundering of personal items in hot water.

Why does the head itch after lice, and how to treat it? - in detail

Scalp irritation following a lice outbreak is primarily a reaction to the insects’ saliva and the remnants of dead parasites. Saliva contains proteins that many individuals recognize as allergens, triggering a histamine‑mediated response that manifests as itching. Additionally, the bodies of deceased lice and shed eggs (nits) accumulate on the skin, providing a physical irritant that aggravates the sensory nerves. Repeated scratching can breach the epidermal barrier, allowing opportunistic bacteria to colonize the area and produce a secondary infection that intensifies discomfort.

Effective management consists of two parallel tracks: eradication of the parasites and mitigation of the inflammatory response.

Parasite elimination

  • Use a pediculicide shampoo or lotion containing 1 % permethrin or 0.5 % malathion, applied according to the product label and left on the scalp for the recommended duration.
  • After the chemical treatment, run a fine‑toothed nit comb through wet hair, section by section, to remove live lice, nits, and debris.
  • Repeat the entire process after seven to ten days to target any newly hatched lice that survived the initial application.

Inflammation control

  • Apply a topical corticosteroid (e.g., 1 % hydrocortisone) to reduce local redness and itching; limit use to a few days to avoid skin thinning.
  • Oral antihistamines (cetirizine 10 mg or diphenhydramine 25 mg) can be taken once daily to suppress the allergic component of the itch.
  • If bacterial infection is suspected—signs include pus, crusting, or spreading redness—administer a topical antibiotic (mupirocin) or seek systemic therapy from a healthcare professional.

Environmental decontamination

  • Wash all bedding, clothing, and towels used during the infestation in hot water (≥60 °C) and dry on high heat for at least 30 minutes.
  • Seal non‑washable items (e.g., hats, stuffed toys) in airtight plastic bags for two weeks to starve any remaining lice.
  • Vacuum carpets and upholstered furniture thoroughly; discard the vacuum bag or clean the canister afterward.

Follow‑up

  • Perform a visual inspection of the scalp and hair three days after the second treatment cycle; any persistent itching should prompt a repeat nit‑comb session.
  • Persistent or worsening symptoms warrant medical evaluation to rule out allergic dermatitis, secondary infection, or resistant lice strains.

Combining thorough chemical or mechanical removal with targeted anti‑itch therapy and strict hygiene practices resolves the majority of post‑infestation discomfort within two weeks.