What Are Ingrown Hairs?
After shaving, short, sharp, and pointed hairs grow out from under the skin. These become ingrown hairs if they grow back into the skin, slightly penetrating the outer skin layer (epidermis). This happens close to the hair follicle, forming dimples, as seen in the figure below .
Ingrown hair scheme from Braunet
Hair can reenter the skin in 2 ways:
- The sharp tip of the hair reenters the skin close to the follicle .
- The shaved hair retracts back directly into the follicle and then goes into the deeper skin layer (dermis) .
Round bumps and small blisters with pus (pustules) may appear at the ingrown site (foreign body inflammatory response) .
Ingrown hairs (also known as Pseudofolliculitis barbae) are most common in individuals of African ancestry (82% versus 18% in Caucasians). In fact, over 50% of men with African ancestry struggle with ingrown hairs [3, 4, 2].
Infected Ingrown Hairs
Ingrown Hair Causes
Some people have genetic mutations in a gene for hair proteins (keratin) in follicles, which increases their risk of ingrown hairs .
Ingrown Hair Treatment
- Steroid cream (corticosteroids) for more severe cases (1 to 3 times a week for 2 weeks) to reduce inflammation
- Acne cream (benzoyl peroxide), alone or with antibiotics, after shaving. This kills the bacteria and calms the skin, reducing the number of round bumps and pustules.
- Antibiotic cream applied once or twice daily if there is an infection
- Vitamin A cream (retinoids) improves the lesions caused by ingrown hairs, helps to prevent scarring, and regenerates the skin.
- Bleaching preparations prevent scarring and tone the skin.
- A glycolic acid lotion is very effective at treating ingrown hairs by softening the skin while allowing individuals to still shave every day.
- Intense pulsed light (IPL) is an effective and safe method for long-term hair-removal. It is especially useful for patients with skin irritation and ingrown hairs
- Laser treatment is a safe and effective option for reducing papules caused by ingrown hairs. The results last up to 3 months after treatment. It’s even more effective when used with a topical cream (eflornithine hydrochloride)
- Electrolysis may work for permanent hair-removal but is not recommended. It is painful, expensive, and generally ineffective in treating ingrown hairs
- Surgical removal is possible, but it is very uncommon.
Treatment Side Effects
- Depilatory creams and chemicals may cause irritation, skin injury, and allergic reactions (dermatitis) .
- Steroid creams (topical corticosteroids) may cause skin thinning and an aged skin appearance. To minimize side effects, steroid creams should not be applied to large areas or over an extended period of time .
- Retinoids should be avoided during pregnancy, as they may cause birth defects .
Ingrown Hair Prevention
- Stop shaving. This is the most effective treatment and cures most cases after one month [1, 9].
- Wash the area with warm water and a mild soap-free cleanser before shaving .
- Use a clean and sharp razor .
- Don’t stretch the skin while shaving .
- Find the best direction for shaving. Shaving in the direction of hair growth is considered the best option; however, 1 study found that men shaving against the grain had fewer bumps .
- Shave only 2 to 3 times per week (versus daily) and with advanced shaving and skin care products that hydrate the skin to reduce ingrown hairs .
- Electrical razors control ingrown hairs, but research about the best shaving tools is scant (single blade vs. double blades and electric vs. manual shaves) .
- Foil-guarded manual razors improve the condition of most patients [19, 1].
- Depilatory creams are a useful alternative to shaving. These hair-removal creams lead to fewer papules than shaving with a razor, but the post-shave irritation is more pronounced .
- Hair-removal creams (such as eflornithine hydrochloride) reduce excessive hair growth and the risk of developing ingrown hairs [20, 21].
Limitations and Caveats
The majority of the study participants were of African descent, so the results may not be applicable to everyone.
Studies comparing single-blade versus multiple-blade razors, or electric versus manual razors, are lacking. Additionally, the best direction of shaving cannot be concluded from current research.