An ingrown hair can turn into a hard lump under the skin when the hair grows back into the skin instead of out of it. This can irritate the hair follicle and trigger swelling, inflammation, or a small cyst-like bump.
The lump may feel firm, sore, itchy, or tender, especially if it becomes infected. Sometimes pus can form, and the area may look red or darker than the surrounding skin. In some cases, a blocked or irritated follicle can develop into a boil or abscess.
Avoid squeezing, picking, or trying to cut the lump open at home, as this can worsen irritation, spread infection, and increase the risk of scarring. Stopping shaving or waxing in the area for a while may help prevent more irritation while the skin heals.
A lump that keeps growing, becomes very painful, drains pus, or does not improve should be checked by a dermatologist or primary care provider. Do not use antibiotics, steroid creams, or acne medications unless they are recommended by a clinician.