Head lice are tiny insects that live in hair on your scalp and neck and nits are the empty egg shells that head lice hatch from. They’re most common in children under 12 but can affect anyone. Read our article below for more information on the causes, symptoms, and treatments for head lice.
What are head lice?
Head lice live in human hair and feed from the blood from your scalp. Anyone can get head lice but they’re most common in children under 12. The ‘peak’ time to get head lice is between 7 and 8 years old, and they are more common in children with long hair.
Adult head lice are usually about the size of a sesame seed and, in a typical case, you’ll likely have around 30 lice on your head. However, if the infestation is severe, there may be more than 1,000 head lice.
Female head lice lay up to 7 – 10 eggs a day which are then attached to your hair strands with a glue-like substance. These eggs then hatch after 1 – 2 weeks and leave behind empty, white egg casings which are known as nits.
Nits can stay stuck to the hair even after the lice have gone, so having nits doesn’t necessarily mean you have an ‘active’ head lice infestation. You only have an active infestation if you find living, moving head lice on your scalp.
Symptoms of head lice
You may not experience any symptoms if you have head lice. Often, people find out by spotting head lice or nits in their hair. You’re most likely to spot head lice or nits on the hairs at the side of your head or the back of your scalp.
Some people also experience itchiness on their scalp, but not everyone does. You may also have small itchy bumps around the edge of your scalp, especially at the back of your neck.
Sometimes you may also feel like something is moving in your hair.
The best way to tell if you do have lice is by using a special fine-toothed comb called a detection comb. The gaps in the teeth of the comb as thinner than the width of adult head lice so when you comb through your hair, the head lice stay on the comb and you will be able to see them.
What causes head lice?
Head lice are spread through head-to-head contact with someone who has them. Head lice can’t jump, fly, or swim, meaning they travel by crawling between hairs. It takes around 30 seconds for a head louse to travel from one person to another.
There is no evidence that head lice prefer clean or dirty hair. You also can’t catch them by sharing hats, combs, or pillows with someone who has head lice. As well as this, head lice only live on humans, so you can’t get them from animals.
How are head lice treated?
Firstly, you should use a detection comb to confirm that you do have head lice. You should check all members of the household for head lice. Follow the instructions on the product packaging to ensure you use it properly.
After confirming the presence of live head lice, you should treat them as soon as possible. There are 2 main options that will work best to treat head lice: medicated lotion or spray, or wet combing.
Medicated lotions and sprays
There are many sprays and lotions you can apply to your hair to kill head lice. These contain an insecticide treatment which may be:
- Dimeticone (Hedrin, NYDA, & Linicin) works by coating the lice so they can’t breathe
- Isopropyl myristate and Cyclomethicone (Full Marks & Vamousse) kills head lice by dissolving their outer wax coating
- Malathion (Derbac-M) is the only chemical insecticide recommended in the UK. It works by poisoning the head lice
Products containing Permethrin, like Lyclear, are not currently recommended as it is believed that head lice are becoming resistant to it. 
Ensure you thoroughly read and follow the instructions that come with your chosen treatment. It’s usually recommended that you treat the head lice twice, 7 days apart, to kill any new lice that may have hatched.
Some preparations aren’t recommended for children under 2, for pregnant or breastfeeding women, or for people who have eczema or asthma. Always read the patient information leaflet and ask a pharmacist If you have any questions.
This treatment involves regularly combing wet hair with a fine-toothed detection comb. If you’re unable to use insecticides, this method may be more suitable for you. You can also reuse the same comb over and over, so one comb can treat all members of a household or recurring infestations. However, wet combing normally doesn’t work as well as using an insecticide and can be time consuming.
Your comb should come with instructions, but typically you’ll need to:
- Wash your hair as normal and then apply a lot of conditioner. Leave this conditioner in until you’ve finished combing.
- Smooth and untangle your hair with your normal comb or hairbrush.
- Comb through sections of the hair, making sure to do the whole head. Strat at the roots and comb all the way to the tips of your hair.
- Check the comb for lice after every stroke. Remove the lice from the comb either by rinsing it or wiping it before combing the next section.
Whichever treatment you use, you should check to see if it has worked afterwards. Using a detection comb, you might want to consider checking after 2 – 3 days and again after 7 days. You should also check everyone in the household again. If you find egg casings it doesn’t mean the treatment hasn’t worked, but if you find live lice you’ll need to treat them again.
Head lice can become resistant to Malathion, so you might want to consider using a different product if you need to treat them again.
It is difficult to prevent getting head lice, although it might help to keep long hair tied up.
The most important thing is to try to catch head lice as early as possible to prevent them from spreading to others.
If you have children under 12 years old, you might want to consider doing regular checks of their hair for head lice or nits. You can also check if they have been in contact with anyone who has head lice. It’s not necessary to keep your child off school if they have head lice, but you should treat them as soon as possible.