An ingrown hair occurs when a hair curls back or grows sideways into the skin instead of emerging normally through the follicle opening. This can cause small, inflamed bumps, tenderness, itching and irritation. When the hair becomes trapped deep beneath the skin and triggers a chronic inflammatory response, a fluid-filled lump called an ingrown hair cyst (pseudocyst) or hair follicle cyst may develop.
An ingrown hair happens when a hair does not grow out of the follicle as expected and instead turns inward or sideways and becomes trapped beneath the skin. The body treats the trapped hair as a foreign object, which can result in inflammation and a visible bump.
Ingrown hairs and ingrown hair cysts are common, especially in areas exposed to frequent hair removal such as shaving, waxing or plucking. Most cases are harmless and respond well to self-care or simple medical treatments. However, persistent, painful or repeatedly infected lumps should be assessed by a healthcare professional.
An ingrown hair cyst (sometimes referred to as a trapped hair cyst or pseudocyst) develops when inflammation caused by a trapped hair leads the body to form a small sac around it. This sac may fill with fluid, pus or keratinous material and can feel firm, tender or swollen.
These cysts are more likely to arise in areas of:
Ingrown hairs affect people of all ages and skin types but are more frequent in those with curly or coarse hair. They are not contagious and are not caused by poor hygiene.
An ingrown hair may present as:
If irritation progresses, some lumps may develop a pus-filled head.
Ingrown hairs develop when:
Shaving against the direction of hair growth, stretching the skin while shaving, or using a blunt razor increases the risk.
Diagnosis is usually clinical and based on appearance and history. A GP or dermatologist will examine the area and assess the appearance of the bumps, their location, and any recent shaving or hair removal practices. This helps distinguish ingrown hairs from acne, folliculitis, cysts unrelated to hair follicles, boils or abscesses, and dermoid or epidermoid cysts. Tests are not normally required.
Most ingrown hairs improve within one to two weeks without treatment.
You can help healing by:
Do not squeeze, pick or dig into the skin, as this increases the risk of infection and scarring.
Medical treatment may be required if:
Treatment options may include:
Persistent or recurrent cysts may require minor surgical removal to prevent further episodes.
Laser hair removal may reduce recurrence in people with frequent ingrown hairs.
The outlook for ingrown hairs and simple ingrown hair cysts is generally excellent.
Ingrown hair cysts that are treated appropriately usually heal well. Recurrence can occur, especially in people who continue hair removal practices that predispose to ingrown hairs.
Complications such as extensive infection or deep scarring are uncommon but may require further medical intervention.
You can reduce the likelihood of ingrown hairs and cyst formation by:
Laser hair removal may be considered for people with persistent or troublesome ingrown hairs.
If you are unsure whether a bump is simply an ingrown hair or something else, a professional assessment can provide clarity. Our clinicians can examine the area and advise on the most suitable treatment options based on your individual skin concerns.
