Lice are easy to confuse with dandruff, which is a very common problem. While lice are a temporary infestation, dandruff is a chronic skin condition.
Every year, 6 to 12 million people in the United States get head lice. Most are children ages 3 to 12 years old.
Both lice and dandruff are usually treatable at home. Distinguishing one from the other can help a person choose the right treatment.
Dandruff, also known as seborrheic dermatitis, is a skin condition that causes the top layer of skin to shed too quickly. This shedding produces a dry, flaky, itchy scalp. People with dandruff may also notice flakes of skin on their clothes.
Yeast causes some types of dandruff that tend to be particularly itchy.
Lice are parasites that live on the scalp and eat human blood. Lice can cause intense itching.
Head lice do not spread diseases, but they are highly contagious. Close contact with the head or hair of a person with lice — such as from sharing hairbrushes or giving hugs — can spread the infestation.
Young children often hug or touch each other, and so head lice are more common in kids than adults and families with kids.
Some important differences between lice and dandruff include:
- Location: Lice lay eggs called nits while dandruff causes flaky skin. The two look similar, but close inspection reveals key differences. Nits stick to the hair while dandruff flakes, easily falling off of hair. While dandruff is visible on the scalp, lice lay eggs on hair, not the scalp.
- Contagion: Dandruff is not contagious, but lice spread easily from person to person. If a classmate, friend, or family member has recently had lice, lice could be the reason why a person develops an itchy scalp.
- Itching: Dandruff and lice both itch. Dandruff tends to itch more when the scalp is dry. People with lice may feel a crawling sensation on their scalp.
- Lymph nodes: Lice can cause bacterial infections, especially when a person scratches their scalp too hard and causes bleeding. Some people with lice notice that the lymph nodes on their neck or behind their ears feel swollen
- Color: Lice are tiny, and people may need a magnifying glass to see them. If a person notices bugs or black or brown spots on the scalp or in the hair, this usually means they have lice, not dandruff.
Some people with dandruff develop seborrheic dermatitis on other areas of their body. When this happens, a person might notice flaking or scaly skin on the face, chest, neck, or ears. These areas may be dry, red, and painful or itchy.
Most people, however, experience a mild form of dandruff only on the scalp. Symptoms of dandruff include:
- flaky skin that is either very oily or very dry
- white or yellowish flakes on clothes
- an itchy scalp
- red patches on the scalp
- symptoms that worsen in the winter or dry weather
Lice are much more common among children and people in close contact with children, such as teachers, parents, daycare workers, and babysitters.
Signs and symptoms of lice include:
- intense itching on the scalp
- constantly scratching the head
- red or bloody spots on the scalp from scratching
- swollen lymph nodes
- teardrop-shaped lice eggs on the hair
- tiny black spots on the scalp or in the hair
A range of insecticidal shampoos can kill lice, sometimes with just one treatment. It is also vital to comb nits out of the hair. People should follow the procedure on the shampoo packaging.
Over-the-counter (OTC) lice remedies work well, but some lice are resistant to these medicines. So if the first treatment does not work, a person may want to see a doctor for an alternative prescription remedy.
Lice remedies are available at pharmacies and online.
Head lice cannot live for long without a host. Washing items that make it easy for lice to hop back onto a person can reduce the spread of these bugs.
The Centers for Disease Control and Prevention (CDC) recommend:
- Washing clothing, bed sheets, and other items in water of 130°F or hotter.
- Soaking brushes and combs in 130°F water for at least 5–10 minutes.
- Vacuuming all carpets and rugs in the home.
- Avoiding using insecticidal sprays or other poisons.
Dandruff often responds well to OTC anti-dandruff shampoos. People can purchase these shampoos in drugstores or online.
The American Academy of Dermatology recommend shampooing with an anti-dandruff shampoo twice a week unless a person is African-American.
African-Americans tend to have drier hair and scalps, so they may be better off shampooing with anti-dandruff shampoo only once per week.
People with light-colored hair should avoid shampoos with coal tar since this can change hair color.
Some people find that their dandruff does not get better with an anti-dandruff shampoo. If symptoms do not improve, the flakes may be due to a yeast infection on the scalp, an autoimmune condition, eczema, or a severe case of dandruff.
A dermatologist can help someone identify the underlying cause, as well as any triggers. Some people may need prescription anti-dandruff shampoos.
Dandruff is common and difficult to prevent. Regularly washing the hair reduces dandruff in some people, but lack of hygiene does not cause dandruff.
People with dandruff can try to identify triggers, such as cold or dry air. People with particularly dry scalps sometimes get relief from sleeping with a humidifier.
To prevent lice, avoid close contact with people at high risk of lice, especially very young children. Avoid sharing combs, brushes, pillows, and other items where lice may hide.
If a person in the family has lice, treat them and other family members for lice.
Neither having lice or dandruff is dangerous. Constant scratching can injure the scalp, however, and may lead to a scalp infection.
Both lice and dandruff usually respond well to store-bought treatments, and so a person can try an OTC remedy as their first response.
If OTC treatments do not work, it is best to see a doctor or dermatologist for scalp itching or pain.