Ingrown Hair Cyst: Causes, Treatments, Prevention

Hair grows out of pores, small openings in the skin that secrete sweat and sebum (oil). An ingrown hair cyst occurs when dirt or oil blocks off a pore, causing a hair to become trapped.

This leads to swelling and looks like a small, red bump. If it becomes infected, an ingrown hair cyst may grow into a large, painful growth. 

Ingrown hair cysts are often treatable at home without medical intervention, but you should see a healthcare provider for cysts that become infected. 

An ingrown hair cyst usually appears as a small bump on the skin. It happens when the hair grows into the skin, causing irritation and swelling. The color may be red, pink, or slightly darker than the surrounding skin. 

An ingrown hair cyst is usually painless and may feel hard or soft. If it becomes infected, it may become painful or tender.

Different types of cysts exist, and their symptoms vary. Types of ingrown hair cysts include:

• Razor bumps: Red, raised bumps along shaved areas of the skin
• Pilonidal cysts: Small white or yellow bumps usually located at the top of the buttocks 
• Epidermoid cysts: Raised bumps on the head, neck, trunk, or genitals; they are the color of the surrounding skin
• Pilar cysts: Round, raised bumps on the scalp that are the same color as the surrounding skin
• Steatocystoma: Smooth yellow or dark-colored bumps along the arms, trunk, or groin area
• Eruptive vellus hair cysts: Small, smooth bumps on the chest, abdomen, arms, or legs; these cysts appear purple on darker skin tones and red or pink on lighter skin tones

An ingrown hair cyst develops when a hair becomes trapped in the skin. It may happen when the skin pore becomes clogged with dirt or oil. A hair may become ingrown when it curls and grows back into the skin. 

Razor Bumps

Pseudofolliculitis barbae, also known as razor bumps, is a common type of ingrown hair cyst. Razor bumps develop when a hair gets stuck in the follicle due to skin irritation from shaving. The hair curls back inside, and a cyst forms.

Razor bumps appear as red, raised bumps. They are most common along the legs, underarms, groin, face, and neck. 

Pilonidal Cysts

Pilonidal cysts occur when a hair punctures and grows into the skin. They usually result from pressure on the skin, such as from tight clothing. Pilonidal cysts most often develop at the top of the buttocks and look like small white or yellow bumps. 

Epidermoid Cysts

Epidermoid cysts develop in the top layer of skin, known as the epidermis. They occur when the hair follicle grows under the skin, trapping the hair.

Epidermoid cysts are usually related to a buildup of keratin, a protein found in the hair follicle. Too much keratin can block the pore and cause a cyst. This type of cyst may also be a sign of Gardner’s syndrome, a rare, inherited disorder. 

Pilar Cysts

Like epidermoid cysts, pilar cysts develop when keratin builds up in the hair follicle. Pilar cysts form at the bottom of the hair follicle and may be genetic.

Steatocystoma

Steatocytoma is a genetic condition that causes cysts in the sebaceous (oil) glands. Some cysts may contain hair follicles due to trapped hair. While these types of cysts are not classified as ingrown hairs, they affect the skin and hair follicles. 

Steatocytoma may be related to a genetic mutation in the KRT17 gene. 

Eruptive Vellus Hair Cysts

Eruptive vellus hair cysts are small cysts that form around very fine hairs known as vellus hairs. The exact cause of vellus hair cysts is unknown. Research suggests they are related to an abnormality in the vellus hair follicles.

Most cases of ingrown hair cysts are mild and resolve on their own. See your healthcare provider if the cyst does not heal or starts to cause pain. Your provider may refer you to a dermatologist, a medical doctor who specializes in diagnosing and treating skin conditions. 

Signs of an infected ingrown hair cyst may include:

• Increased redness or discoloration
• Pus or liquid oozing out
• Inflammation 
• Pain
• Itching 
• Foul odor
• Fever 

If your cyst has not improved after 1-2 weeks, a dermatologist may be able to drain the cyst to help with pain and healing. They may also prescribe an antibiotic medication if the cyst is infected. If your cyst is a sign of another health condition, your provider will refer you to a different specialist. 

Ingrown hair cysts are treatable, and many resolve on their own. The goal of treatment is to reduce inflammation and prevent infection. Ingrown hair cysts caused by an underlying health condition will likely not improve until the condition is effectively treated. 

To heal razor bumps, try these steps:

• Stop shaving that area until the cysts resolve
• Keep the area clean and dry 
• Use a gentle moisturizer
• Apply a warm compress to soften the skin
• Never try to pop a cyst, as it could lead to infection
• Consider using an over-the-counter (OTC) hydrocortisone cream to reduce swelling

If the ingrown hair cyst does not improve at home, you may need to see your healthcare provider for treatment.

Preventing all ingrown hair cysts may not be possible, but you can reduce your risk and prevent complications. 

Because shaving may lead to ingrown hair cysts, consider other hair removal methods, such as laser hair removal. If you choose to shave, only use sharp razors, as dull ones increase the risk of ingrown hairs. Always use a gentle shaving cream or gel when shaving. Apply unscented body lotion or cream after shaving. 

Wash your skin with warm (not hot) water using a gentle cleanser. Consider using an exfoliating treatment to remove dead skin cells and minimize the risk of clogged pores. 

The most common complication of an ingrown hair cyst is infection. A cyst can become infected if bacteria on the skin become trapped in the hair follicle. A skin infection may cause pain, itching, swelling, and other symptoms.

See your primary healthcare provider if you believe that your cyst may be infected. Treatment options are available. 

Ingrown hair cysts occur when hair becomes trapped in the follicle due to a clogged pore. Shaving irritation is a common cause of ingrown hair cysts.

To treat an ingrown hair cyst at home, keep the area clean and dry. Avoid shaving that area of skin, and use warm compresses as needed.

See your healthcare provider if you develop any signs of infection, such as pus, increased swelling, or a fever.