Head Lice

Medication Information Leaflet

What are Head Lice?

Head lice are caused by the species Pediculus humanus capitis, which are wingless, crawling insects that live close to the human scalp and feed on blood from the human scalp. Head lice can live up to 30 days while their eggs can live more than two weeks on humans. Their bites can be itchy.

However,  having head lice is not a sign of poor hygiene and head lice do not carry or spread other diseases. Anyone can catch head lice at any age but they most commonly affect children.

What are the possible causes of this condition?

Female head lice lay their eggs close to the scalp, on hair strands. The eggs stick to the hair strands and hatch in about 7 days. Eggs are most often laid behind the ears and at the back  of the neck. These eggs are also called nits.

Head lice are mostly spread by head-to-head contact with someone who already has head lice. 

What are the symptoms of head lice?

The symptoms of this condition can include the following:

  • An itchy scalp. 
  • Moving head lice on scalp or hair. They can be 2-3mm long and appear greyish-white to reddish-brown in colour
  • Small pale eggs stuck to bases of hair strands.
  • Skin sores caused by scratching.

Finding hair lice by wet combing

  • Apply enough hair conditioner to cover each hair strand from root to tip. Apply the conditioner evenly and detangle hair using a normal comb. Conditioner can be applied to wet or dry hair.
  • Divide the hair into 3-4cm sections and starting at the scalp, comb each section using a fine toothed lice comb.
  • After each stroke, wipe the conditioner off the comb onto a paper towel and look for lice and eggs. Remove all eggs and lice from the comb after each stroke.
  • Repeat the combing at least twice for every part of the head.

What can I do to treat head lice?

Head lice can be treated in the following ways and you can approach your pharmacist to get the following medications. 

  • Malathion
  • Benzyl benzoate

When do I need to see a doctor?

Although head lice can be treated without a doctor’s consultation, there are times where the condition might be more serious. 

If your condition does not get better after the use of a head lice product or gets worse, you should see a doctor. You should also see a doctor if you experience any of the following:

  • Weeping or crusting on the skin
  • Swollen glands 
  • Fever

What else can I do to manage this condition?

Other than using medications to treat the condition, head lice can also be managed by the following methods:

  • Check hair for hair lice and eggs using wet combing. Repeat the combing every two to three days and continue to check for two to three weeks to be sure that all lice and eggs are removed.
  • Soak combs or brushes in hot water for 5 to 10 minutes.
  • Soak and wash clothing, bed sheets and towels in hot water and dry in a hot dryer for at least 20 minutes or place the personal objects in a sealed plastic bag for two weeks to starve the lice.

The following are some suggestions to prevent hair lice from happening again:

  • Do not share hats, hairbrushes, combs and pillows
  • Carry out weekly hair and scalp checks when lice are present in your community
  • Keep long hair tied back


This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

The content above is solely for informational purposes only and is not intended as a substitute for the advice provided by your physician, pharmacist or other healthcare professional. You should not use the information for diagnosing or treating a health problem or disease, or prescribing any medication or other treatment. Always speak with your physician, pharmacist or other healthcare professional before taking any medication or supplement, or adopting any treatment for a health problem.

Last updated on November 2023

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