What Causes Ingrown Hairs? Triggers, Risks, and Treatment

Ingrown hairs happen when a cut or plucked hair grows back into the skin instead of out. The result is a small, tender bump—sometimes with a visible hair loop—that can itch, sting, or fill with pus if it gets irritated or infected. They’re especially common after shaving, waxing, or tweezing, and in areas with friction from clothing. Anyone can get them, but they’re more likely with coarse or curly hair and in the beard area, bikini line, underarms, and legs.

This guide breaks down what actually causes ingrown hairs, from the way hair grows to everyday triggers, and why they can appear even if you don’t shave. You’ll learn who’s at higher risk, how to tell ingrown hairs from folliculitis or cysts, and what complications to watch for (like infection, dark marks, and keloids). We’ll share do’s and don’ts, at-home steps that help release the hair, a skin-friendly shaving routine, lower-risk hair removal options, area-specific tips, and when medical care makes sense—so you can prevent bumps and keep skin calm.

How ingrown hairs form under the skin

Ingrown hairs form when a removed hair starts to grow back and curves into the skin instead of out. Shaving, waxing, or tweezing takes away the visible shaft but leaves the follicle; the new tip is sharp. If the follicle curves or the strand is curly, the regrowing hair can bend sideways and pierce nearby skin or get trapped under a layer of dead skin. Pulling skin tight while shaving can also make the cut hair snap back below the surface. Your body treats the in-growing tip like a splinter—sparking irritation, a tender bump, itching, and sometimes pus—this reaction is what causes ingrown hairs. Sometimes you’ll even see a tiny looped hair under the skin.

Common triggers: shaving, waxing, tweezing, and friction

Most ingrown hairs start with hair removal that leaves a sharp tip or disturbs the follicle. Shaving cuts hair at an angle, while waxing and tweezing yank it out so the next growth can curl and re-enter the skin. Close or dry passes irritate follicles; tight clothing can amplify the problem. These are the everyday triggers behind what causes ingrown hairs.

Shaving: Close, multi-blade strokes and skin-stretching create sharp tips that pierce skin.
Waxing: If a hair snaps below the surface, regrowth often veers sideways.
Tweezing: Broken hairs and angled regrowth make looped hairs more likely.
Friction/pressure: Waistbands, seams, and athletic gear press stubble into follicles and inflame bumps.

Why you can get ingrown hairs even if you don’t shave

Even without shaving, ingrown hairs can form as naturally curly strands re-enter the skin during regrowth, especially from curved follicles. A layer of dead skin can block the opening so the tip grows sideways under the surface. Non-shaving hair removal like waxing or tweezing triggers the same loop-back. They can also appear on areas you don’t groom—such as the buttocks or scalp—because hairs there still regrow and sometimes curve inward.

Risk factors: hair type, skin tone, and shaving technique

The biggest driver of what causes ingrown hairs is hair shape. Curly or coarse strands and curved follicles make the regrowing tip more likely to arc back into skin, which is why the condition is especially common in Black people and others with tightly curled hair. Skin of color is also more prone to razor bumps (pseudofolliculitis barbae) after close shaves. Technique matters: very close, multi‑blade shaves, pulling skin taut, shaving against the grain, dry shaving, dull blades, and frequent shaving all increase risk. Tweezing and waxing can do the same if hairs break below the surface and regrow at an angle.

Where they appear and what they look like

Ingrown hairs most often show up where hair is shaved or rubs against clothing: beard area (face/neck), bikini line/pubic area, underarms, legs, chest/back, buttocks, and even the scalp. They appear as small, raised, tender bumps that can itch or sting; some fill with pus. You may see a trapped or looped hair under the skin. Redness is common on lighter skin; brown or purple discoloration on darker skin is typical and may linger.

Ingrown hairs vs. folliculitis, razor bumps, and cysts

Bumps after hair removal often look alike, but they aren’t the same. Most trace back to what causes ingrown hairs—sharply cut or curly strands curving into the skin—yet the labels point to different patterns and next steps. Knowing whether you’re seeing a single ingrown hair, true folliculitis, classic razor bumps, or a cyst helps you choose between gentle release, anti-irritation care, or medical treatment.

Ingrown hair: A single tender bump or small pustule; you may see a looped or trapped hair under thin skin.
Folliculitis: Clusters of small red or pus-filled bumps centered on follicles; often itchy or burning and can be bacterial.
Razor bumps (pseudofolliculitis barbae): Inflammatory papules after close shaving, especially in curly beards; can lead to dark marks.
Ingrown hair cyst: A deeper, round, painful lump that can fill with pus and persist; seek care if hot, very swollen, or you feel unwell.

Possible complications (infection, hyperpigmentation, keloids)

Most ingrown hairs clear on their own, but repeated irritation or picking can turn a small bump into a bigger problem. The in‑growing tip acts like a splinter, driving inflammation that can invite infection and lead to scarring. People with tightly curled hair and skin of color are also more prone to lingering dark marks and keloids.

Infection: Bumps enlarge, hurt more, feel warm or swollen, and may ooze pus; antibiotics may be needed.
Postinflammatory hyperpigmentation: Brown or purple spots that outlast the bump, especially on darker skin.
Keloids and other scars: Raised, firm scars (sometimes darker than surrounding skin) or fine depressed grooves after repeated inflammation.

Seek care if an area is very painful, hot or swollen, or if you have fever, chills, or feel unwell.

Do’s and don’ts when you spot an ingrown hair

Pause hair removal and hands off. Treat it like a splinter: calm the area, keep skin clean, and watch for infection. These quick do’s and don’ts help keep a small bump from turning painful or scar‑prone.

Do: Warm compresses 10–15 minutes to soften skin and calm irritation.
Do: Gentle exfoliation to help free the tip; avoid harsh scrubs.
Don’t: Pick, squeeze, dig, or shave over it—this raises infection and scarring risk.

At-home treatments that help release the hair

Your goal is to free the trapped tip without injuring skin or seeding infection. Most bumps settle on their own, but these gentle steps help the hair release sooner and reduce tenderness.

Pause hair removal: Stop shaving, waxing, and tweezing until the bump calms.
Warm compresses (10–15 minutes): Soften skin and reduce irritation once or twice daily.
Gentle exfoliation: In warm water, use a soft washcloth or mild scrub in small circles to clear dead skin over the follicle.
If a loop is visible: Clean the area, sterilize a fine needle or tweezers with rubbing alcohol, and gently lift one end of the hair out—don’t dig.
Clean and protect: Dab a mild antiseptic and minimize friction from tight clothing.
Watch for infection: Worsening pain, heat, swelling, or pus means it’s time to seek care.

Prevention basics: a skin-friendly shaving routine

A few smart tweaks can cut down the sharp tips and follicle irritation that drive what causes ingrown hairs. Think: soften hair, lubricate well, use a sharp single blade with gentle technique, and cool the skin after. This reduces friction, prevents too‑close cuts, and helps hairs grow outward.

Soften first: Wash with warm water or hold a warm, damp cloth for 2–3 minutes, then apply a shaving gel or cream to soften hairs.
Choose the right blade: Use a sharp, single‑blade razor and replace blades regularly to avoid tugging and micro‑nicks.
Don’t stretch skin; go with the grain: Shave in the direction of hair growth using light pressure and short strokes.
Limit passes and keep it clean: Use as few strokes as possible and rinse the blade after each pass.
Avoid ultra‑close shaves: Leave a hint of stubble and skip daily shaving when you can.
Finish right: Rinse, press on a cool, wet cloth for about 5 minutes, then apply a soothing after‑shave or a glycolic acid lotion to gently exfoliate.

Hair removal alternatives that reduce risk (clippers, depilatories, laser, electrolysis)

If shaving keeps triggering bumps, switch to methods that don’t cut hair so close to the skin. These options lower the chance that a sharp tip will curve back and cause what causes ingrown hairs in the first place.

Electric clippers or razors: Avoid the closest setting and hold slightly off the skin. Leaving a hint of stubble greatly reduces ingrowns.
Depilatories (creams): These dissolve hair proteins instead of cutting the shaft. Patch test first—chemicals can irritate—and follow timing exactly.
Laser hair removal: Heat targets pigmented follicles, reducing regrowth and ingrowns over time; works best on dark hair. Often recommended for recurrent cases.
Electrolysis: A fine needle delivers a mild electrical zap to destroy individual roots. Effective for stubborn hairs, but slow for large areas.

Special situations: bikini line, underarms, legs, and beard area

Some zones are simply higher risk because hairs are curlier, skin is moist or compressed, and shaving angles are awkward. Tuning your technique by area reduces the sharp tips and irritation that drive what causes ingrown hairs—and helps hairs grow out, not in.

Bikini line: Trim or clip close instead of ultra‑close shaving. Shave with the grain, avoid skin‑stretching, skip tight underwear right after, and use a cool compress.
Underarms: Hair grows in several directions—use short, light strokes following growth patterns with a slick gel, then cool the skin.
Legs: Never dry shave; soften first and use a sharp single blade with gentle pressure. Rinse well and apply a soothing or glycolic lotion.
Beard area: High risk for razor bumps. Don’t pull skin; shave with the grain using a single blade, or switch to clippers and leave slight stubble. Avoid daily shaves if prone.

When to see a healthcare provider and typical medical treatments

See a healthcare provider if a bump doesn’t improve with home care, keeps recurring, becomes very painful, hot or swollen, or drains pus. Seek urgent care with fever, chills, or if you feel unwell. Get help too for scarring, dark marks, or when you’re unsure whether it’s folliculitis or a cyst.

Antibiotics: Topical or oral options for infected follicles.
Retinoids: Prescription creams to exfoliate and free trapped hairs.
Steroid creams: Short courses to calm inflammation.
Sterile release: In‑office needle/scalpel lift of the hair.
Laser or electrolysis: Longer-term reduction of regrowth and recurrences.

Over-the-counter options and hydrocolloid patches

Over-the-counter care won’t change what causes ingrown hairs, but it can calm irritation, help the tip surface, and prevent infection. Keep it simple and gentle while the bump settles.

Chemical exfoliants: Light glycolic or salicylic acid lotions help clear dead skin so hairs grow out, not in. Start slowly.
Soothers and barriers: Use a slick shaving gel and a bland moisturizer to reduce friction. A mild antiseptic can help keep skin clean if it’s oozing.
Hydrocolloid patches: For tender, pus-filled bumps, a patch absorbs fluid, seals out friction, and discourages picking. Apply to clean, dry skin and change daily. It won’t “pull” the hair out—stop if worsening and seek care for signs of infection (heat, swelling, spreading redness, fever).

Key takeaways

Bottom line: ingrown hairs happen when sharp, regrowing strands curve into skin—most often after close shaving and in curly hair. Keep bumps rare by softening, shaving with a single blade and light pressure, and switching to lower‑risk methods when needed. For gentle skincare support and hydrocolloid patches that help protect irritated bumps while they heal, visit the Mollenol homepage.

Back to blog