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Head lice are contagious parasites that exist in three forms:
- eggs, also called “nits:” tiny white specks
- nymphs, or young adults: small, tan-colored insects hatched from nits
- adult lice: still extremely small, about the size of a sesame seed
Dandruff, also called seborrheic dermatitis, is a self-contained scalp condition that causes flaky skin or scales on your scalp. You can’t catch dandruff from anyone else, although it tends to run in families.
Read on to learn the differences between lice and dandruff. Knowing the differences can help you treat your scalp condition properly.
Head lice and dandruff can cause noticeable symptoms in some people, but not in others. Itching is the most common symptom associated with both conditions. Lice feed on human blood and stay close to the scalp. The insects’ saliva irritates the scalp and causes you to itch. Dandruff can itch if your scalp is very dry.
The causes of dandruff and lice are different.
Lice are parasitic insects that crawl and spread to others through close contact. Lice can crawl onto:
- personal items like combs, hats, and hair accessories
It’s very easy to get head lice from a family member who has them.
Dandruff is a noncontagious, noninflammatory skin condition. Excessively dry or oily skin, common skin yeast, and certain genetic factors are commonly associated with dandruff.
Dandruff typically affects adolescents and young adults, but older adults and small children can also experience a flaky scalp. Cradle cap, a type of dandruff, is common in newborns and babies.
Check all members of your household if someone has lice, especially if you share the same bed. Lice transfers easily from person to person.
Treatment for head lice can come in the form of medicated shampoos. Shampoos containing permethrin and pyrethrin kill lice and nits and are recommended for adults and children over 2 years of age. You may have to wash your hair with the medicated shampoo again after 7 to 10 days to ensure that all the lice are dead.
To apply treatment, you should:
- Remove clothing that may become wet or stained during application.
- Apply the medicine according to instructions on the box. You may need a second bottle if you are treating longer hair.
- Check for live lice 8 to 12 hours after application. Comb out dead and live lice using a fine-tooth comb.
It is often advised to continue treatment until all the lice and nits are gone. Depending on your medication, a follow-up treatment is recommended about 7 to 9 days after the first treatment or if you see crawling lice.
You may require over-the-counter (OTC) or prescription medication. These medications include:
- pyrethrins, available OTC
- 1 percent permethrin lotion, available OTC
- 5 percent benzyl alcohol lotion, prescription
- 0.5 percent ivermectin lotion, prescription
- 0.5 percent, malathion lotion, prescription
- 0.9 percent, spinosad topical suspension
Nonmedical remedies can be used in addition to medicated shampoos to help prevent head lice from spreading.
A lice infestation requires a little more work around the house to make sure that all of the tiny insects and their eggs are destroyed.
Wash clothing, towels, and bedding in very hot water and dry them on a high heat setting. Vacuum upholstered furniture and carpeting, and bag up stuffed animals and other toys for at least 3 days and up to 2 weeks. Any remaining lice will die without food.
You can also manage dandruff with special shampoos designed to slow the skin-shedding process or treat fungal infections that might lead to skin flaking. Look for shampoos with coal tar, salicylic acid, ketoconazole, or selenium sulfide. Use dandruff shampoos every day to control severe flaking or weekly to manage minor symptoms.