When do lice start causing itching? - briefly
Itching usually begins 4–7 days after lice have established themselves, when the insects feed and inject saliva. Most individuals notice the sensation within a week of infestation.
When do lice start causing itching? - in detail
Lice become a source of discomfort shortly after they attach to the scalp and begin feeding. Adult females lay eggs (nits) close to the hair shaft; hatchlings (nymphs) emerge within 7–10 days. The first sensation of irritation typically appears within 24–48 hours of the initial bite, as the insect injects saliva containing anticoagulants and anesthetic compounds.
The progression of itch can be outlined as follows:
- Day 1–2: Saliva introduced during feeding triggers a mild localized reaction; a faint tingling may be perceived.
- Day 3–5: Repeated bites increase the concentration of allergens; the scalp becomes increasingly sensitive, producing a noticeable pruritus.
- Day 6 onward: Accumulation of waste material and bacterial colonisation intensify inflammation; itching becomes persistent and may spread to surrounding skin.
Individual factors modify the onset and severity of the sensation:
- Skin sensitivity: persons with heightened allergic responses experience itching sooner.
- Infestation density: a larger number of insects accelerates the buildup of saliva and waste, prompting earlier irritation.
- Personal hygiene: infrequent washing allows debris to accumulate, worsening inflammation.
Typical signs accompanying the itch include small red papules at bite sites, a dry or flaky scalp, and occasional secondary lesions from scratching. Persistent scratching can lead to excoriations, secondary bacterial infection, and hair loss if left untreated.
Effective control measures focus on eliminating the parasites and reducing inflammation:
- Apply a pediculicide approved for scalp use, following the manufacturer’s instructions for repeat treatment after 7–10 days to target newly hatched nymphs.
- Comb wet hair with a fine-toothed lice comb to remove nits and live insects.
- Use an anti‑inflammatory or antihistamine topical preparation to alleviate the pruritic response.
- Maintain regular shampooing and avoid sharing personal items such as combs, hats, or pillows.
Early detection, prompt treatment, and diligent follow‑up prevent the itch from becoming chronic and reduce the risk of complications.