An ingrown hair happens when a hair shaft curls back into the skin or gets trapped beneath the surface instead of growing outward. The result is a small, often inflamed bump that can be painful, itchy, or easily mistaken for acne. While almost anyone can get one, the causes range from your natural hair texture to the way you shave to something as simple as the clothes you’re wearing.
How a Hair Becomes Ingrown
There are two basic ways a hair goes wrong. In the first, a hair exits the follicle normally but then curves back down and pierces the skin nearby. In the second, the hair never makes it out at all. It grows sideways inside the follicle and burrows into the surrounding tissue without breaking the surface.
Either way, your body treats the trapped hair tip like a foreign invader. The immune system sends inflammatory cells to the area, which is why ingrown hairs produce red, swollen bumps and sometimes fill with pus. If the cycle repeats in the same spot over months or years, it can eventually leave a small scar or a darkened patch of skin.
Hair Texture Is the Biggest Risk Factor
The single strongest predictor of ingrown hairs is having tightly curled hair. A curved hair follicle produces a strand that naturally spirals as it grows. When that strand is cut short (by shaving, for instance), the sharpened tip follows its curl right back toward the skin and can re-enter it within days. People with straight, fine hair can still get ingrown hairs, but the odds are significantly lower because the strand tends to grow away from the surface rather than looping back.
This is why pseudofolliculitis barbae, the clinical name for chronic ingrown hairs in the beard area, predominantly affects Black men. Certain variations in keratin genes (the proteins that give hair its structure) further increase susceptibility. The condition produces clusters of small papules and pustules along the jawline and neck that are often confused with a bacterial skin infection. Women with tightly curled hair face the same issue, especially in the bikini area and along the legs.
How Shaving Creates the Problem
Shaving is the most common trigger, and the type of razor you use matters more than most people realize. Multi-blade razors are designed with a “lift and cut” mechanism: the first blade hooks the hair and pulls it slightly upward, and the following blades slice it off. The stub then snaps back below the skin surface. That might deliver a closer shave, but it also means the freshly cut tip is already sitting beneath the skin line, giving it a head start on growing inward instead of outward.
Shaving against the grain compounds the effect. It forces the blade to pull each hair further from its natural resting position before cutting, which increases how far the stub retracts. Shaving dry skin without lubrication adds friction, which can push cut hairs sideways. Dull blades require more passes over the same area, irritating the skin and increasing the chance of trapping a hair.
Waxing and Plucking Carry Their Own Risks
Removing hair from the root sounds like it would solve the problem, but waxing and tweezing introduce a different version of it. When a new hair regrows inside a follicle that has been traumatized by plucking, the follicle’s internal structure may be slightly distorted. The hair can grow at an odd angle, miss the opening of the follicle entirely, and curl into the surrounding tissue. Waxing large areas at once, like the bikini line or underarms, creates dozens of these slightly damaged follicles simultaneously, which is why ingrown hairs often appear in clusters a week or two after a wax.
Dead Skin Traps Hair Beneath the Surface
Even without shaving or waxing, a hair can become ingrown if it simply can’t push through the skin above it. Dead skin cells and a protein called keratin naturally accumulate on the surface. When this buildup is thick enough, it forms a physical plug over the follicle opening. The hair keeps growing but has nowhere to go, so it turns sideways under the skin.
People with naturally oily skin may be more prone to this type of ingrown hair because excess oil (sebum) mixes with dead cells to form an even stickier barrier. Dry skin can cause the same problem for different reasons: without enough moisture, the outer layer becomes rigid and harder for a fine hair to penetrate. Regular exfoliation, whether with a gentle scrub or a washcloth, helps clear that layer and gives new hairs a clearer path out.
Tight Clothing and Friction
Clothing that presses tightly against freshly shaved or waxed skin can physically push emerging hairs back into the follicle. The pubic area is especially vulnerable because underwear elastic, leggings, and fitted jeans create constant pressure and friction throughout the day. That friction also irritates the skin’s surface, promoting the kind of minor swelling that narrows follicle openings and makes it harder for hairs to emerge cleanly.
This is one reason ingrown hairs are more common in the bikini zone than on, say, the forearms. It’s not just that the hair there is coarser. It’s also that the skin rarely gets a break from contact with fabric.
Hormones and Hair Thickness
Hormonal shifts can change how thick and fast your hair grows, which indirectly raises your risk of ingrown hairs. Androgens, the group of hormones that includes testosterone, stimulate thicker, coarser hair production. When androgen levels are elevated, or when hair follicles are unusually sensitive to normal androgen levels, you may notice denser growth in areas like the chin, chest, or bikini line. Thicker hair has a stiffer shaft that is more likely to pierce back into skin after being cut, and faster growth means the cycle repeats more quickly.
Conditions like polycystic ovary syndrome (PCOS) and certain adrenal gland disorders can raise androgen levels in women, leading to excess hair growth called hirsutism. People managing hirsutism through frequent shaving or waxing often find themselves dealing with ingrown hairs as a secondary frustration, since both the hair characteristics and the removal methods are working against them.
Body Areas Most Affected
Ingrown hairs can show up anywhere you have hair, but certain spots are far more common targets:
- Beard and neck: Tightly curled facial hair combined with daily shaving makes this the most frequent site in men. The neck is particularly prone because hair there often grows in multiple directions, making it nearly impossible to shave “with the grain” everywhere.
- Bikini line and pubic area: Coarse hair, curved follicles, frequent removal, and constant friction from clothing all converge here.
- Legs and underarms: Large surface areas shaved quickly, often with multi-blade razors, produce a high volume of cut hairs that can become trapped.
- Buttocks and inner thighs: Friction from sitting and walking keeps pressure on follicles throughout the day.
Preventing Ingrown Hairs
The most reliable prevention strategy targets whichever cause applies to you. If shaving is the trigger, switching to a single-blade razor eliminates the lift-and-cut effect that pulls hair below the skin. Shaving with the grain, using a sharp blade, and never shaving dry skin all reduce the chance of a hair retracting too far. Leaving slight stubble rather than chasing a perfectly smooth shave gives hairs enough length to clear the skin surface as they grow.
If dead skin buildup is the issue, gently exfoliating the area every few days with a soft brush or mild scrub keeps follicle openings clear. Moisturizing after hair removal keeps the skin pliable so new hairs can push through more easily. In areas where tight clothing is unavoidable, choosing breathable fabrics and looser fits for the first day or two after shaving or waxing gives the skin a chance to recover without added pressure.
For people with very curly hair who deal with chronic ingrown hairs despite these steps, longer-term hair removal methods like laser treatments can reduce the volume of hair that regrows, which lowers the number of opportunities for hairs to become trapped. Growing hair out slightly longer, when lifestyle or workplace rules allow it, is the simplest solution of all: a hair that’s never cut short rarely has a sharp enough tip to re-enter the skin.