Head lice can be difficult to treat due to the time-consuming and precise nature of treatment and high re-infestation rate.

In the past, traditional insecticides were used to treat head lice infestations but head lice would often develop resistance to them.

Therefore, these types of treatments have virtually been replaced with silicone and oil-based preparations which have a physical rather than a chemical action on lice.

After a head lice infestation has been confirmed you can treat the lice at home by wet combing the hair with a head lice comb or by using a lotion or spray that's designed to kill head lice (see below).

However, neither will protect against re-infestation if head-to-head contact is made with someone with head lice during the treatment period.

Wet combing

The wet combing method involves removing the head lice by systematically combing the hair using a special fine-toothed comb.

The comb's teeth should be spaced 0.2-0.3mm apart. Lice can be crushed or trapped between the teeth of nit combs with a tooth spacing of less than 0.19mm and remain unseen. 

You can buy a fine-toothed comb from your local pharmacy or you can order one online.

Lotions or sprays don't need to be used for wet combing. However, to be effective, wet combing needs to be carried out regularly and thoroughly. The method you should use is described below. 

• Wash the hair using ordinary shampoo and apply plenty of conditioner, before using a wide-toothed comb to straighten and untangle the hair.
• Once the comb moves freely through the hair without dragging, switch to the louse detection comb. Make sure the teeth of the comb slot into the hair at the roots, with the bevel-edge of the teeth lightly touching the scalp.
• Draw the comb down to the ends of the hair with every stroke, and check the comb for lice.
• Remove lice by wiping or rinsing the comb.
• Work methodically through the hair, section by section, so that the whole head is combed through.
• Rinse out conditioner and repeat the combing procedure.
• Repeat the procedure on days three, six, nine, 12 and 15, so that you clear young lice as they hatch, before they have time to reach maturity.

How long it will take to comb your child’s hair will depend on the type of hair they have and its length. For example, short, straight hair can be quickly prepared and can be fine-toothed combed in a few minutes. Longer, curlier hair will take longer to comb.

Lotion or sprays

Using a lotion or spray is an alternative method of treating head lice. However, to be effective they need to be used correctly. Your pharmacist will be able to recommend an over-the-counter lotion or spray and advise you about how to use it correctly.

A lotion or spray should only be used if a living (moving) head louse is found. Crème rinses and shampoos aren't thought to be effective and therefore aren't recommended.

Ensure you have enough lotion or spray to treat everyone in your family who's affected. Use enough to coat the scalp and the length of the hair during each application.

Follow the instructions that come with the lotion or spray when applying it. Depending on the product you're using, the length of time it will need to be left on the head may vary from 10 minutes to eight hours.

The normal advice is to treat the hair and repeat the treatment after seven days. Some products also supply a comb for removing dead lice and eggs.

Some products may be capable of killing eggs as well as lice, although there's no certainty of this. Check for baby lice hatching from eggs three to five days after using a product and again 10-12 days afterwards.

At least two applications of lotion are needed to kill lice over the hatching period because the lotions don't always kill louse eggs.

If the lice appear unaffected by the product, or if the problem persists, seek advice from your school nurse, health visitor, pharmacist or GP.

Cautions

Always read the instructions on the pack or leaflet that comes with a head lice treatment, particularly in relation to the following groups:

• young babies (under six months old)
• pregnant women
• people with asthma or allergies

If you're still unsure, seek advice from a healthcare professional before using the product.

It's recommended that pregnant women use either wet combing or 4% dimeticone lotion, which is licensed for use during pregnancy and breastfeeding.

Afro hair

Afro (frizzy) hair or hair that's tightly curled can make treating a head lice infestation particularly difficult.

There's no evidence that keeping your child's hair short, or plaiting or braiding it, will make it easier to treat.

Afro hair should be treated in a similar way to straight hair. Methodically combing small sections of hair at a time with a lice comb, and/or using a lotion or spray, will usually prove effective.