Head Lice and Nits - Symptoms

What are the symptoms of head lice?

Many people with head lice do not have any symptoms. An itchy scalp occurs in some cases. This is due to a skin reaction to the lice bites or saliva, not due to their biting as such, or their movement on your head. It can take about three months for an itch to develop after you are infested with lice. Therefore, you may not notice that you have head lice for a while and you may have passed them on to others by the time you are aware of them. Head lice and nits do not wash off with normal shampoo.

Head lice do not usually cause any other medical problems. Very occasionally, the scratching can cause a rash on the scalp, and occasionally this can cause an infection, and/or glands in the neck can get bigger in response. It can be embarrassing for children or parents to admit they have found head lice. Sometimes parents can be too embarrassed to tell the school, or their children's friends. This may encourage spread, as others may not be aware they have been exposed. Sometimes repeat infestations can be frustrating for children and their families.

The number of lice that may be on one person can vary greatly. There may be just a few in some; in other cases there are more than 100. Very rarely in very severe cases there may be over 1,000. Typically in the UK, there are around 30 lice present on each affected person's head.

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Dr Mary Harding
Peer Reviewer:
Dr Laurence Knott
Document ID:
4263 (v43)
Last Checked:
24 August 2016
Next Review:
24 August 2019

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.