Bacteria cause some common infections, such as folliculitis and impetigo. Others, such as ringworm, are fungal.
Symptoms vary between infections, though most cause redness, itching, and sometimes pus. Recognizing the differences can help a person get the right treatment. Applying specialized creams or ointments or using a medicated shampoo can usually clear up scalp infections.
In this article, we look at the causes, symptoms, and treatments for some scalp infections.
Image credit: CDC, 1959.
Image credit: CDC/ Dr. Lucille K. Georg, 1964.
Image credit: Lforlav, 2011.
Image credit: Åsa Thörn, 2011.
Image credit: Rusty.t.miller, 2009.
Image credit: Gene H Kim MD, Radha Mikkilineni MD, 2010.
Image credit: Gambichler et al., 2010.
Ringworm is a fungal infection that causes a ring-shaped mark on the skin. It can affect any part of the body, including the scalp.
Ringworm that affects the scalp is known as tinea capitis.
Ringworm can cause a scaly, red, bald patch anywhere on the scalp. This can spread across the scalp, producing many separate spots. Ringworm on the scalp is more likely to affect children than adults.
A person can get the infection from another person, an animal, or a damp environment, such as a public pool. To reduce the risk of ringworm, people should not share towels or other personal items with someone who has ringworm.
To reduce the risk of getting ringworm from an animal, a person should wash their hands after contact with pets or other animals. If a person suspects that their pet has ringworm, they can take them to a vet for treatment.
Creams, lotions, and powders will not clear up a ringworm infection on the scalp. A doctor will usually prescribe antifungal tablets to treat ringworm on the scalp. According to the Centers for Disease Control and Prevention (CDC), a person may need to take this medication for 1 to 3 months.
The hair on the body and the scalp grow out of hair follicles. Bacteria can enter the skin through damaged hair follicles, causing an infection called folliculitis.
People can get folliculitis on their scalp from:
- shaving or plucking hair on the scalp
- frequently touching the scalp
- wearing tight hats or other headgear
- having hot, damp skin for an extended time
Folliculitis causes a red ring to develop around each hair follicle. This may cause pain or itching.
People may find relief from redness and itching by applying a warm washcloth to the skin. In some cases, a person may need to take medication for the infection, but it will usually clear up on its own.
If a person knows what has caused their folliculitis, they can prevent and treat the condition more easily. For example, if they have recently shaved their head, they can make an extra effort to prevent bacteria from entering the skin. This may include washing more frequently or changing headgear more often.
Washing hands frequently can help prevent the spread of impetigo.
Impetigo is a common skin infection that often affects children. It is a contagious bacterial infection.
Staphylococcus bacteria live on the skin and are mostly harmless, but they can cause an infection if they enter damaged skin.
Another bacterium called Streptococcus can also cause impetigo. This bacteria can spread from person to person by skin contact, touching objects, or sneezing and coughing.
Impetigo most commonly affects the face, particularly the area around the nose and mouth, but it can affect any part of the body where the skin is broken. This includes the scalp. Impetigo can also spread from the original site to other areas of the body.
Impetigo causes red sores on the skin that burst, leaving a yellow-brown crust. It can also cause large, fluid-filled blisters that break open and leave a sore. These sores and blisters often itch and can be painful.
Impetigo is highly contagious. A person can avoid passing on the infection by staying away from school or work, washing their hands often, and covering sores or blisters with a bandage.
A doctor can prescribe an antibiotic cream to treat impetigo. A person applies this cream directly to the affected areas of skin. The American Academy of Dermatology note that this treatment will stop a person from being contagious within 48 hours. Signs of impetigo should clear up in around a week.
Sometimes, a person may need to take antibiotic tablets. In rare cases, a doctor may recommend antibiotic injections.
4. Fungal infections
In rare cases, a person may develop a fungal infection on the scalp caused by a fungus found in the environment. One example is mucormycosis, a rare infection caused by fungi found in soil.
The fungus can enter the body through broken skin, such as a cut or skin condition. Symptoms include:
- blisters or ulcers on the skin
- warmth around the infection
People who have a weakened immune system are at higher risk of developing a fungal infection. People can reduce their risk of developing fungal infections by keeping cuts or broken skin clean and covered. This is particularly important when working outside or around soil.
A doctor will usually treat fungal infections with antifungal medication. In severe cases, they may inject antifungals into the blood.
5. Seborrheic dermatitis
This common skin condition causes dry, flaking skin. Seborrheic dermatitis can cause redness and may itch.
Cradle cap, which develops on a baby's scalp is a form of seborrheic dermatitis.
In adults, seborrheic dermatitis is the most common cause of dandruff.
Cradle cap usually disappears by itself. If a doctor recommends treatment, it will usually involve shampooing the baby's scalp, gently brushing away the scales when they are soft, or applying medication to their scalp.
For dandruff, using a mild dandruff shampoo and gently removing flakes of skin can help. If the condition is severe or gets in the way of a person's daily life, people can see a doctor for advice. A doctor may prescribe medicine to apply to the scalp for short periods or recommend barrier-repair cream to strengthen the skin on the scalp.
6. Scalp psoriasis
Smoking can trigger psoriasis flares.
Psoriasis is a long-term skin condition caused by a problem with the immune system. According to one estimate, around half of the people who have psoriasis develop it on their scalp. The skin appears thicker in patches, red in color, and may have silver scales.
People can treat psoriasis using topical skin creams, light therapy, and medication taken by mouth. Avoiding psoriasis triggers, such as skin injury, stress, and smoking can help to reduce the symptoms of psoriasis.
7. Lichen planus
Lichen planus is a skin condition that causes shiny, red-purple plaques on the skin. Developing lichen planus on the scalp is rare. However, if it does develop on the scalp, it usually causes:
- thinning hair in the area
- skin irritation
- red-purple bumps
It is not clear what causes lichen planus. The condition often goes away without treatment. However, topical creams and antihistamines can relieve uncomfortable symptoms. A doctor may prescribe corticosteroid pills or shots, retinoic acid creams, or light therapy.
Scleroderma is a condition that causes the body to make too much collagen. This makes the skin harder and tighter than usual. It is not yet clear what causes this rare disease, but it may have links to the immune system. The tissue underneath the thicker skin usually disappears, leaving a line on the scalp or face.
Scleroderma that affects the scalp is known by the French term en coup de sabre. This refers to the lines of thicker skin that resemble marks made with a specific type of sword called a saber.
Treatment can include light therapy, medication, or fillers to restore the skin's original appearance.
Scalp infections can be uncomfortable, but treatment is usually straightforward. Seeing a doctor or dermatologist as soon as symptoms appear can help with a quick diagnosis and treatment.