Para-aminobenzoic acid (PABA)

While some complementary and alternative techniques have been studied scientifically, high-quality data regarding safety, effectiveness, and mechanism of action are limited or controversial for most therapies. Whenever possible, it is recommended that practitioners be licensed by a recognized professional organization that adheres to clearly published standards. In addition, before starting a new technique or engaging a practitioner, it is recommended that patients speak with their primary healthcare provider(s). Potential benefits, risks (including financial costs), and alternatives should be carefully considered. The below monograph is designed to provide historical background and an overview of clinically-oriented research, and neither advocates for or against the use of a particular therapy.

Related Terms

  • 2,3,5,6-Tetrafluorophenyl n-(s-benzoylthioacetyl)glycylglycyl-p-aminobenzoate, 4-aminobenzoic acid, 4-aminobenzoic acid hydrazide, ABAH, Actipol®, Aktipol®, aminobenzoate potassium, aminobenzoic acid, BAB, BT-PABA, buytl aminobenzoate, cyclic amino acid, disulfate ester of ursodeoxycholyl-p-aminobenzoic acid, disulphate ester of ursodeoxycholyl-p-aminobenzoic acid, ester oxybenzone, ethyl p-aminobenzoate, ethyl dihydroxypropylaminobenzoate, glyceryl para-aminobenzoate, KPAB, K-para-aminobenzoate, monoglyceryl para-aminobenzoate, n-benzyol-l-tyrosyl-p-aminobenzoic acid, NBT-PABA, n-butyl-p-aminobenzoate, n-diethyl-methyl-ammonium ethyl bromide-p-[2(n-octyloxy)-benzoyl-]aminobenzoate, octyl dimethyl PABA, PABA ester, Pabafil®, PABA-UDCA, padimate O, PAMBA, p-aminobenzoic acid, para aminobenzoic acid, para-aminobenzoate, para-aminobenzoate potassium, paraaminobenzoic acid, para-aminobenzoic acid, para-aminomethylbenzoic acid, PEG-25 PABAs, Peptide-PABA, Photoplex, POTABA®, potassium para-aminobenzoate, synthetic peptide Bz-Ty PABA, UDCA-PABA, ursodeoxycholic acid-p-aminobenzoic acid, vitamin Bx, vitamin H.

  • Metabolites: Para-acetoamidobenzoic acid (PAABA), para-acetamidohippuric acid (PAAHA), para-aminohippuric acid (PAHA).

  • Derivatives of PABA commonly used for therapeutic purposes: BAB (butyl aminobenzoate, for epidural injection), KPAB (potassium para-aminobenzoate, for taking by mouth), padimate O (PABA ester, for use on the outside of the body), PAMBA (para-aminomethylbenzoic acid, for taking by mouth or intramuscular use).

Background

  • Para-aminobenzoic acid (PABA) is a naturally occurring nonprotein amino acid. Although early studies suggested that PABA was a B vitamin, PABA is now known to be neither a vitamin nor an essential nutrient. Although dietary PABA deficiency is not an issue in humans, PABA is found in foods such as liver, kidney, wheat germ, bran, and yogurt. Sulfonamide antibiotics interfere with the reproduction of some bacteria by interfering with PABA conversion into folic acid, the latter of which is required for DNA synthesis.

  • Historical uses of PABA included treatment of hair loss and restoration of color to graying hair, with variable effectiveness. PABA first emerged as a sunscreen after World War II due to its ability to absorb ultraviolet B light. However, it was soon recognized that PABA was a “sensitizer” and stimulated allergic reactions. PABA was also suspected of being a causative agent in several autoimmune diseases. Consequently, PABA gradually ceased to be used in sunscreens, which were then marketed as being “PABA free.”

  • PABA has also been used in a variety of diagnostic laboratory tests and as a structural component of many drugs. PABA has shown promise as a potential treatment for melasma. Melasma is a darkening of the skin in sun-exposed areas of the body, particularly the face. When melasma occurs in pregnant women, it is known as “the mask of pregnancy.” PABA has also shown promise in the treatment of inflamed corneas associated with a herpes virus infection and in the prevention of recurrent herpes infections that cause sores on the mouth, lips, and gums.

Scientific Evidence

Uses

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Herpes (keratitis)

Actipol® is a 0.007% PABA solution for eye use that has been studied for the treatment of inflamed corneas caused by the herpes virus. The solution has been found to be effective in curing most patients. Further studies may provide additional useful information on the use of PABA for this condition.

Melasma (prevention)

Preliminary data suggest that PABA may be effective in the prevention of melasma (also known as chloasma) in pregnant women. Melasma is a darkening of the skin on sun-exposed areas of the body, particularly the face. When melasma occurs in pregnant women, it is known as “the mask of pregnancy.” Additional studies are needed before a conclusion can be made.

Recurrent herpes labialis infection (prevention)

Sun exposure has been shown to stimulate the reactivation of a herpes simplex virus infection on the lips, as well as in the mouth or gums. Limited research suggests that PABA in sunscreen may be effective in preventing recurrent herpes labialis. Further studies will provide additional useful information on the use of PABA for this condition.

Asthma

Preliminary evidence suggests that para-aminomethylbenzoic acid (PAMBA; a PABA derivative that is taken by mouth or injected into muscle) may help prevent worsening of asthma symptoms following a bronchoprovocation challenge (a test to determine whether a patient has asthma). Further studies are needed before a conclusion can be made.

Autoimmune disorders (pemphigus vulgaris adjuvant)

Preliminary data suggest that para-aminomethylbenzoic acid (PAMBA; a PABA derivative that is taken by mouth or injected into muscle) might allow patients with the autoimmune blistering disease pemphigus vulgaris to reduce their steroid dosage. Additional studies are needed in this area.

Cancer pain

The PABA derivative n-butyl-p-aminobenzoate (BAB) can be injected into the epidural space of the spine and used as a local anesthetic. Preliminary data suggest that BAB treatment may provide significant pain relief to cancer patients who are experiencing pain that is difficult to manage. Further research is necessary before a conclusion can be made.

Hair loss

Preliminary evidence suggests that a combination product containing PABA (Pantogar®; containing PABA, B vitamins, calcium-d-pantothenate, vigar yeast, L-cystine, and keratin) may be effective in the treatment of hair loss. Further research on the effect of PABA alone is needed.

Inflammatory skin disorders (lichen sclerosus)

Limited research suggests that potassium para-aminobenzoate (KPAB; a PABA derivative taken by mouth) may be effective in the treatment of lichen sclerosus, a skin condition that is characterized by inflammation, itching, and pain, particularly in the anogenital area. Additional research is needed in this area.

Peyronie’s disease

Limited research suggests that potassium para-aminobenzoate (KPAB; PABA derivative taken by mouth) may improve the symptoms of Peyronie’s disease. Peyronie’s disease is a connective tissue disorder that primarily affects the penis, causing pain, curvature of the penis, and sexual dysfunction. Additional studies are needed before a conclusion can be made.

Scleroderma

Studies investigating the use of potassium para-aminobenzoate (KPAB; a PABA derivative taken by mouth) as a treatment for skin changes in scleroderma have shown mixed results. Further high-quality research is needed to determine if PABA may be useful in the treatment of this condition.

Sun protection

PABA was best known for its use as a component of sunscreen products for the skin. However, there are few studies demonstrating its effectiveness for this purpose. The use of PABA in sunscreen has been reduced due to the reportedly high frequency of allergic reactions and cross-sensitivity with other medications. Further studies may help to better characterize the sun-protective properties of PABA.

*Key to grades:

Tradition

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

  • Anesthetic, anti-inflammatory, antimalarial, antioxidant, antitumor, blood thinner, chemotherapy adjuvant (sensitizes tumor cells to chemotherapy/radiation), chemotherapy side effects reduction (reduces DNA breaks from chemotherapy), dental plaque (homeostasis), dermatomyositis (muscle disease characterized by inflammation and rash), fertility, heart disease, kidney stones (prevention), poisoning (antidote for Paraquat poisoning), skin cancer prevention, systemic sclerosis, vitiligo (condition in which patches of skin lose pigment).

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

  • Several derivatives of para-aminobenzoic acid (PABA) are available to be taken by mouth, including para-aminomethylbenzoic acid (PAMBA), potassium para-aminobenzoate (also known as KPAB or POTABA®), N-benzoyl-L-tyrosyl-PABA (also known as peptide-PABA, for diagnostic testing of pancreas function), and ursodeoxycholic acid-p-aminobenzoic acid (also known as UDCA-PABA, used for diagnostic testing of bacterial overgrowth). Because it is excreted primarily by the kidney, dosage adjustment of PABA taken by mouth or injected into a vein or muscle may be necessary in patients with impaired kidney function.

  • For asthma, one gram of para-aminomethylbenzoic acid (PAMBA) has been taken by mouth prior to a challenge test (a test to determine if patient has asthma).

  • For Peyronie’s disease, 12 grams of POTABA® (prescription-strength potassium salt of PABA) has been taken by mouth with meals daily in four divided doses for 8-24 months.

  • For scleroderma, 8-12.5 grams of potassium para-aminobenzoate (KPAB) has been taken by mouth with meals daily for 1.25-26.6 months.

  • For inflamed corneas associated with a herpes virus infection, two drops of Aktipol® (0.007% PABA solution) have been placed drop by drop into the conjunctival sac of the eye 8-10 times daily, together with injections in select cases.

  • For treatment of pemphigus together with standard treatment, 100-200 milligrams of intramuscular para-aminomethylbenzoic acid (PAMBA) has been used daily for 7-26 days.

Children (under 18 years old)

  • There is no proven safe or effective dose for para-aminobenzoic acid (PABA) in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • Avoid with known allergy or hypersensitivity to para-aminobenzoic acid (PABA) and its derivatives para-aminomethylbenzoic acid (PAMBA), butyl aminobenzoate (BAB), padimate O (octyl dimethyl PABA), potassium para-aminobenzoate (KPAB or POTABA®), N-benzoyl-L-tyrosyl PABA, Aktipol®, and ursodeoxycholic acid-PABA.

  • PABA and compounds derived from it are believed to be fairly common sensitizers, causing irritant and hypersensitivity reactions. However, it is unclear if the majority of allergic reactions due to topical PABA use are due to PABA itself or due to other substances in these products, including various preservatives or alcohol.

  • Ester local anesthetics, such as benzocaine, are associated with an increased incidence of allergic reactions due to their metabolism to PABA. Patients allergic to ester local anesthetics should be given preservative-free amide agents.

  • Photocontact and contact sensitization (increased sensitivity of a patient’s skin to light and chemicals) and allergies, including contact and photocontact dermatitis, due to topical PABA derivatives (such as the anesthetic butyl aminobenzoate (BAB)) have been described.

  • In patients with sensitivity to PABA, continued exposure may result in the development of autoimmune diseases, such as dermatomyositis (a muscle disease characterized by inflammation and rash) and systemic lupus erythematosus.

Side Effects and Warnings

  • Para-aminobenzoic acid (PABA) taken by mouth is generally well tolerated. The most commonly reported side effects are diarrhea, nausea, vomiting, fever, and rash. Doses taken by mouth may need to be adjusted in patients with impaired kidney function.

  • Rare cases of methemoglobinemia (a condition in which oxygen transport to tissues is impaired) have been reported in patients receiving local anesthetics containing PABA derivatives.

  • Abnormalities of liver function tests, gastrointestinal upset, headache, jaundice, lower white blood cell count, and vitiligo (condition in which patches of skin lose pigment) have been reported.

  • In patients with sensitivity to PABA, continued exposure may result in the development of autoimmune diseases, such as dermatomyositis (a muscle disease characterized by inflammation and rash) and systemic lupus erythematosus.

  • Although not specifically associated with topical use of PABA, it should be noted that the likelihood for vitamin D deficiency increases with chronic sunscreen use.

  • Pharmaceutical doses of PABA and its derivatives should only be taken under the supervision of a qualified healthcare provider.

  • Discontinue if rash, nausea, or anorexia occur.

  • PABA given intravenously may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or those taking drugs, herbs, or supplements that may increase the risk of bleeding. Dosing adjustments may be necessary.

  • PABA may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

  • Use with caution in patients with kidney disease, because PABA is eliminated from the body primarily through the kidneys.

  • Use cautiously when taking by mouth in doses greater than eight grams daily, as rare cases of liver toxicity have been reported.

  • Avoid taking at the same time as sulfonamide antibiotics, as it may reduce their effectiveness.

  • Avoid giving to children by mouth, particularly at doses greater than 220 milligrams per kilogram of body mass daily, as there is an increased risk of serious side effects.

  • Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence.

  • Avoid with known allergy or hypersensitivity to para-aminobenzoic acid (PABA) and its derivatives: para-aminomethylbenzoic acid (PAMBA), butyl aminobenzoate (BAB), padimate O (octyl dimethyl PABA), potassium para-aminobenzoate (KPAB or POTABA®), N-benzoyl-L-tyrosyl PABA, Aktipol®, and ursodeoxycholic acid-PABA.

Pregnancy and Breastfeeding

  • Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

  • Para-aminobenzoic acid (PABA) may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, antiplatelet drugs such as clopidogrel (Plavix®), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

  • PABA may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

  • PABA may also interact with anesthetics, antacids, anticancer drugs, antihistamines, anti-inflammatory agents, antivirals, bronchodilators, cortisone, cytotoxic agents, dapsone, digestive enzymes, estradiol, fibrotic disease agents, gastrokinetic agents, interferon, light-sensitizing agents, methotrexate, para-phenylenediamine, sun-protective agents, pirenzepine, procainamide, procaine-penicillin, sulfonamides, tinidazole, or topical drugs.

Interactions with Herbs and Dietary Supplements

  • Para-aminobenzoic acid (PABA) may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

  • PABA may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

  • PABA may also interact with anesthetics, anticancer agents, anti-inflammatory herbs and supplements, antioxidants, antivirals, cortisol-inducing or cortisol-suppressing agents, cytotoxic agents, digestive enzymes, folic acid, gastrokinetic agents, hormonal herbs and supplements, light-protective agents, light-sensitizing agents, and topical agents.

Author Information

  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Akberova SI. [Actipol in treating stromal herpetic keratitis]. Vestn Oftalmol 2002;118(2):17-19. View Abstract
  2. Cole C. Multicenter evaluation of sunscreen UVA protectiveness with the protection factor test method. J Am Acad Dermatol 1994;30(5 Pt 1):729-736. View Abstract
  3. Fleming SC, Kapembwa MS, Griffin GE. Combined single day 14C-triolein breath test and PABA test in the diagnosis of malabsorption. Ann Clin Biochem 1990;27 ( Pt 1):50-55. View Abstract
  4. Fric P, Malis F, Kasafirek E, et al. A new method of testing pancreatin therapy in vivo by the use of a peroral chymotrypsin substrate 4-(N-acetyl-L-tyrosyl)aminobenzoic acid. Hepatogastroenterology 1980;27(3):220-223. View Abstract
  5. Hoek FJ. The PABA test for evaluation of exocrine pancreatic function: a review of the literature. Neth J Med 1988;32(3-4):143-156. View Abstract
  6. Hoek FJ, van den Bergh FA, Klein Elhorst JT, et al. Improved specificity of the PABA test with p-aminosalicylic acid (PAS). Gut 1987;28(4):468-473. View Abstract
  7. Kataoka K, Yamane Y, Kato M, et al. Diagnosis of chronic pancreatitis using noninvasive tests of exocrine pancreatic function–comparison to duodenal intubation tests. Pancreas 1997;15(4):409-415. View Abstract
  8. Khan NA, Kruse JA. Methemoglobinemia induced by topical anesthesia: a case report and review. Am J Med Sci 1999;318(6):415-418. View Abstract
  9. Kimura T, Wakasugi H, Ibayashi H. Clinical study of exocrine pancreatic function test by oral administration by N-benzoyl-L-tyrosyl-p-aminobenzoic acid. Digestion 1981;21(3):133-139. View Abstract
  10. Kitagawa M, Naruse S, Ishiguro H, et al. Evaluating exocrine function tests for diagnosing chronic pancreatitis. Pancreas 1997;15(4):402-408. View Abstract
  11. Kluczyk A, Popek T, Kiyota T, et al. Drug evolution: p-aminobenzoic acid as a building block. Curr Med Chem 2002;9(21):1871-1892. View Abstract
  12. Larsen B, Ekelund S, Jorgensen L, et al. Determination of the exocrine pancreatic function with the NBT-PABA test using a novel dual isotope technique and gas chromatography-mass spectrometry. Scand J Clin Lab Invest 1997;57(2):159-165. View Abstract
  13. Platteeuw JJ. Resistance to sulphadrug-based antifolate therapy in malaria: are we looking in the right place? Trop Med Int Health 2006;11(6):804-808. View Abstract
  14. Schauder S, Ippen H. Contact and photocontact sensitivity to sunscreens. Review of a 15-year experience and of the literature. Contact Dermatitis 1997;37(5):221-232. View Abstract
  15. Weidner W, Hauck EW, Schnitker J. Potassium paraaminobenzoate (POTABA) in the treatment of Peyronie’s disease: a prospective, placebo-controlled, randomized study. Eur Urol 2005;47(4):530-535. View Abstract

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.