If you’re dealing with scalp psoriasis, a head lice infestation is the last thing you need. You’re already managing an itchy scalp, dandruff, sores, and other skin symptoms, and now you and your loved ones have to stop an outbreak.

Head lice are tiny insects that live on the scalp, where they feed on blood. Head lice can cause symptoms that are similar to those of scalp psoriasis, such as itching. Head lice also lay tiny eggs, called nits, that stick to individual hair shafts. These nits can look like the skin flakes caused by scalp psoriasis. However, nits cannot be easily combed out of the hair.

Medicated shampoos are used to treat both scalp psoriasis and head lice. However, the compounds used to kill head lice are very different from those used to treat scalp psoriasis. Only one ingredient used to treat scalp psoriasis — coal tar — is useful against head lice, and it does not directly kill lice.

Head Lice Shampoos

Head lice are usually treated with over-the-counter insecticide shampoos that contain pyrethrins or pyrethroids. Pyrethrins are chemicals found in chrysanthemum flowers that are toxic to insects. Pyrethroids are synthetic pyrethrins that also work to kill bugs. The popular lice shampoo Nix contains the pyrethroid permethrin.

If over-the-counter shampoos don’t kill all the lice, prescription treatment options are available, including:

• Benzyl alcohol lotion
• Ivermectin lotion
• Malathion lotion
• Spinosad (Natroba)

Shampoos for Scalp Psoriasis

Shampoos for psoriasis do not contain any of the lice-killing ingredients listed above. Most over-the-counter psoriasis shampoos contain coal tar or salicylic acid.

Coal tar is a coal byproduct that has been used to treat psoriasis, including scalp psoriasis, for more than 100 years. It is especially useful for treating the itch associated with scalp psoriasis. Coal tar also decreases skin cell growth, which can help prevent plaques.

Salicylic acid reduces skin irritation and helps remove dead cells. It’s useful for weakening thick psoriasis patches, working to peel away layers.

Prescription shampoos are available for severe cases of scalp psoriasis. The main ingredient is clobetasol propionate, a steroid that reduces inflammation.

Do Scalp Psoriasis Shampoos Kill Lice?

While shampoos with coal tar, salicylic acid, or topical steroids are useful medical treatments for psoriasis, none of them work directly to kill lice. You cannot wash your hair with your medicated shampoo for scalp psoriasis and expect a lice infestation to go away. However, one type of scalp psoriasis treatment — coal tar shampoo — can be used as part of a lice treatment regimen.

Coal Tar Shampoo for Lice Detection and Removal

Coal tar shampoo won’t kill lice, but it can help you find them. Head lice are tiny, and it can be very hard to see adult lice on the scalp. Lice are usually detected by the presence of nits, their eggs, which look like small seeds stuck onto individual hairs close to the scalp.

However, because people with scalp psoriasis can have lots of skin flakes, it can be difficult to tell nits apart from flakes. Shampooing with coal tar shampoo before doing a lice inspection can help remove flakes, making it easier to detect nits if they are there.

Coal tar can also be a helpful part of a wet combing treatment for head lice. Wet combing involves lubricating the hair with a thick substance, like hair conditioner or olive oil, and then combing the hair with a special fine-tooth comb designed to remove lice. This combing removes both live lice and lice eggs.

Wet combing lice and nits from the scalp may not totally eliminate lice, and it should always be done in combination with a medication treatment.

Coal tar shampoo isn’t thick enough to be used for wet combing, but it can help relieve irritation caused by lice. It can be a useful cleansing treatment before applying olive oil, hair conditioner, or other treatments for a wet comb. Some coal tar shampoo users report seeing lice that are “stunned” after coal tar shampoo treatment, but there is no medical evidence that coal tar directly kills head lice. Do not use coal tar shampoo alone to treat head lice.

Some studies suggest that coal tar can increase cancer risk if a person is exposed to very high concentrations, such as the amount used for roofing and road paving. The American Academy of Dermatology reports studies have not shown this risk of cancer in using coal tar at low levels for treating psoriasis.

Talk With Others Who Understand

MyPsoriasisTeam is the social network for people with psoriasis, and their loved ones. On MyPsoriasisTeam, more than 126,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis.

Have you dealt with both scalp psoriasis and head lice at once? Do you have any advice for others? Share your experience in the comments below, or start a conversation by posting on your Activities page.