PABA (Para-Aminobenzoic Acid)
What is it? Overview Usage Side Effects and Warnings

What is PABA (Para-Aminobenzoic Acid)?

Para-aminobenzoic acid (PABA) is best known as the active ingredient in sunblock. This use of PABA is not really medicinal: like a pair of sunglasses, PABA physically blocks ultraviolet rays when it is applied to the skin.

There are, however, some proposed medicinal uses of oral PABA supplements. PABA is sometimes suggested as a treatment for various diseases of the skin and connective tissue, as well as for male infertility. However, most of the clinical data on PABA comes from very old studies, some from the early 1940s.

PABA has been suggested as a treatment for Peyronie's disease , a condition in which the penis becomes bent owing to the accumulation of fibrous plaques 1 However, there has been only one reported double-blind placebo-controlled study properly examining this use. (For information on why such studies are essential, see Why Does This Database Rely on Double-Blind Studies? ) This trial enrolled 103 men with Peyronie's disease and followed them for one year. The results showed that use of PABA at a dose of 3g 4x daily significantly slowed the progression of Peyronie’s disease; it did not, however, reduce pre-existing plaque.

PABA has also been suggested as a treatment for scleroderma , a disease that creates fibrous tissue in the skin and internal organs. 2 A 4-month double-blind,...

Safety Issues

PABA is probably safe when taken at a dosage up to 400 mg daily. Possible side effects at this dosage are minor, including skin rash and loss of appetite. 3 Higher doses are a different story, however. There has been one reported case of severe liver toxicity in a woman taking 12 g daily of PABA. 4 Fortunately, her liver recovered completely after she discontinued her use of this supplement. Also, a recent study suggests that 8 g daily of PABA can cause vitiligo, the patchy skin disease described previously. 5 Clearly, there are questions that need to be answered about the safety of high-dose PABA therapy. You shouldn’t take more than 400 mg daily except under medical supervision.

PABA may interfere with certain medications, including sulfa antibiotics . 6...