Para-aminobenzoic acid (PABA), also known as vitamin B10, is an organic compound found in certain foods and produced by the chemical industry.

It was once added to sunscreen and has been used as a supplement to help darken gray hair and improve certain skin issues, among other uses.

This article provides an overview of the functions of PABA, its possible benefits and downsides, and dosage and safety information.

Vitamin B10 (or vitamin Bx) is an alternative name for the organic compound PABA, a white crystalline substance.

It’s considered part of the vitamin B complex, although it’s not a vitamin nor an essential nutrient. It’s found in brewer’s yeast, organ meat, mushrooms, whole grains, and spinach (1, 2).

Your body can also synthesize the compound using certain bacteria in your gut. PABA then assists in the production of folate (vitamin B9). Yet, the amount of folate produced is inadequate to meet your needs, so you need to obtain it from other dietary sources (1, 3).

PABA is thought to benefit skin and hair when taken as a supplement. It’s industrially produced and sold in pill, powder, extract, and topical application form (1).

Summary

PABA is an organic crystalline compound also known as vitamin B10, although it’s not truly a vitamin. It’s found in some foods and produced chemically for lotions and supplements.

While there are several proposed benefits of PABA supplements, limited studies support these claims.

Sun protection

PABA can absorb ultraviolet (UV) rays — especially UVB rays, which are associated with sunburns and DNA damage. It was thus a key ingredient in sunscreen starting in the 1940s but later linked to allergic skin reactions in some people (4, 5).

Since 2019, PABA is no longer generally recognized as safe and effective for use in sunscreen by the Food and Drug Administration (FDA) (6).

It’s sometimes found in certain lotions and other products marketed as moisturizers, often in combination with aloe vera, and it’s rarely used in shampoos, conditioners, and lipsticks (7).

Skin-related disorders

Besides protecting against UV rays, PABA is claimed to help with skin issues related to hardening, tissue buildup, and discoloration — although how the compound may improve these conditions remains unclear (8).

For one, PABA has been investigated for its use in the treatment of Peyronie’s disease, which is characterized by the buildup of fibrous plaque inside the penis (9).

One study found that taking a potassium PABA supplement significantly decreased plaque size in individuals with Peyronie’s disease over 12 months, compared with a placebo (10).

That said, more research is needed, and PABA is currently thought to be ineffective for treating this condition (11).

PABA has also been identified as a possible treatment for scleroderma, an autoimmune disease that causes hardening of the skin and fibrous deposits in the organs (8).

One retrospective study in 467 people with scleroderma found that 90% of those who received potassium PABA supplements experienced mild, moderate, or marked skin-softening, compared with 20% of a control group (12).

Even so, this is one of the only studies on the topic, and it was conducted over 30 years ago. Other research has suggested that PABA has no effect on skin hardening associated with scleroderma, so additional research is needed (8).

Finally, PABA is often touted as a treatment for vitiligo, a condition marked by depigmentation and white patches on the skin. While some people with this disorder claim that PABA supplements help, limited scientific studies support the claim (13).

Hair care

One of the earliest uses of PABA supplements was to help with the repigmentation of prematurely gray hair. It’s still used for this purpose today, and many personal testimonies suggest it’s effective despite a lack of research.

Studies in the 1940s and ’50s found that taking PABA at daily doses ranging from 200 mg to 24 grams led to hair darkening and helped gray hair return to its original color (14, 15, 16).

It’s important to note, though, that some research found that hair became gray again after participants discontinued the supplement (14).

What’s more, even though PABA was shown to darken gray hair in early studies, this effect has not been studied recently. Some researchers concluded that PABA should not be taken for the sole purpose of darkening hair, due to its unknown side effects (14, 17).

Summary

PABA can absorb UVB rays and was once added to sunscreens. Some studies suggest that when taken orally, PABA can help with skin issues and darken gray hair, but research is limited.

Some people have had allergic reactions to sunscreens containing PABA, causing red, itchy rashes (18, 19).

Today, PABA is no longer added to sunscreen in the United States and rarely found in cosmetics. Some individuals may be sensitive to higher oral supplement doses of PABA, but human research is needed.

Taking high doses of PABA supplements is not considered safe for those with liver and kidney issues.

There have been at least six case reports of acute liver injury after the use of PABA supplements for Peyronie’s disease. However, this side effect may not apply to those without underlying conditions who take PABA (20).

It’s also important to note that PABA is considered an ineffective treatment for this disease, based on available research (11).

Additionally, it’s thought that PABA can accumulate in the kidneys, although there are no scientific sources that pertain to this claim. Thus, those with liver or kidney issues should not take PABA without medical supervision (21).

What’s more, PABA may interact with sulfonamides (sulfa drugs), including certain antibiotics, and decrease their effectiveness. They should not be taken together (22).

Finally, the safety of PABA supplements in children and pregnant or breastfeeding women is unknown. These populations are not advised to take PABA orally, but the topical application of the compound is likely safe.

If you’re using a cosmetic product that contains PABA and you notice a rash or skin irritation, discontinue its use.

Summary

Some individuals may have an allergic reaction to the topical application of PABA. High doses of oral supplements may damage the kidneys and liver.

Minimal research supports the use or benefit of PABA oral supplements. As such, there’s not a recommended or standardized dosage.

Most PABA supplements on the market recommend 500 mg per day but range from 100 mg to over 1,000 mg.

However, the FDA doesn’t regulate supplements as strictly as it regulates medications. Thus, the dosages and ingredients listed on a PABA supplement may not match what’s in the bottle.

Always speak to a healthcare provider before starting a PABA supplement, especially since the long-term effects of the compound aren’t well understood.

Summary

The effects of PABA are not fully understood, and there’s no standardized dosage for PABA supplements.

PABA, also known as vitamin B10, is an organic compound found in some foods and supplements.

In the past, it was a common ingredient in sunscreen, as it blocks UVB rays. Limited research also suggests that PABA supplements may help darken grey hair and improve skin issues that involve tissue buildup and hardening.

While topical applications and most supplements are considered generally safe, the effects of PABA are not fully understood. High doses may lead to harmful side effects.