Para-aminobenzoic acid (PABA) is a naturally occurring, non-protein amino acid. It was once thought to be a B vitamin, but is now known to be neither a vitamin nor an essential nutrient in humans. Dietary PABA deficiency is not an issue in humans, though PABA can be found in liver, kidney, wheat germ, bran, and yogurt.
PABA is most well-known as a part of some sunscreen products, since it can absorb ultraviolet (UV) light. PABA is also part of many different agents, including those that treat abnormal heart rhythms, bacterial infection, seizures, nausea and vomiting, cancer, mental illnesses, stomach issues, and pain.
PABA is involved in the creation of folic acid in bacteria. It has also been used as a marker in urine to determine the function of the pancreas and bacterial overgrowth. PABA has also been used to assess liver function and identify liver failure.
PABA has shown promise as a potential treatment for melasma (patches of dark skin on the face) and herpetic keratitis (eye inflammation caused by the herpes virus), as well as the prevention of recurring cold sores. PABA has also been studied for Peyronie's disease (painful, abnormal curving of the penis), scleroderma (build-up of scar tissue in the skin), chronic pain, lichen sclerosis (white patches on the skin), pemphigus (autoimmune disorder causing skin blisters), and asthma. There is less evidence to support the use of PABA for dermatomyositis (a muscle disease causing inflammation and skin rash), hair loss, and systemic sclerosis (a connective tissue disease causing skin thickening). Some evidence suggests that PABA may have blood-thinning, anti-inflammatory, anti-malarial, and anti-tumor effects, as well as its potential coloring benefits for graying hair.
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.
Sun exposure may reactivate herpes simplex virus infection of the mouth. PABA-containing sunscreens may help prevent the recurrence of cold sores, since PABA is known to absorb UV light. Further research in this area would be useful to make firm conclusions.
Early study in pregnant women suggests that PABA may help prevent melasma, which is thought to worsen with sun exposure. PABA helps block UV light absorption. However, research is limited and further information is needed.
Potassium PABA may have anti-inflammatory effects that may benefit people with Peyronie's disease. Several studies have found a positive effect from treatment with potassium PABA. However, there are some mixed results. Further study is needed to make firm conclusions on the use of PABA for the management of Peyronie's disease.
Arachidonic acid, an omega-6 fatty acid, appears to play an important role in the development of asthma. PABA (in the form of PAMBA, para-aminomethylbenzoic acid) may help decrease levels of arachidonic acid, thereby reducing inflammation in people with asthma. Further studies are needed to confirm these findings.
Pemphigus vulgaris is an autoimmune disease that causes blisters and sores on the skin. It is thought that PABA (in the form of PAMBA, para-aminomethylbenzoic acid) may benefit people with this condition and reduce the need for steroids. However, more studies are needed in this area.
Early research suggests that PAMBA may have anti-tumor effects in people with superficial bladder cancer (SBC), a cancer of the inside lining of the bladder. Improvements have been seen in tumor recurrence and overall survival. However, even with these benefits, further study is needed to make firm conclusions.
PABA in the form of n-butyl-p-aminobenzoate (BAB) has been studied for the management of long-term pain. Early research found significant pain relief after injecting BAB in people with cancer-related pain. Further study is needed to confirm these findings.
Early evidence suggests that a combination product containing PABA (Pantogar®) may be effective in the treatment of hair loss. Further research on the effect of PABA alone is needed.
Actipol®, a PABA-containing solution, has been studied for the treatment of eye pain and inflammation caused by the herpes virus. The solution has been found to be effective for most people. Further studies may provide more useful information on the use of PABA for this condition.
Limited research suggests that PABA in the form of potassium para-aminobenzoate (KPAB) may be effective in the treatment of lichen sclerosus, an inflammatory skin disorder. More research is needed in this area.
PABA in the form of potassium para-aminobenzoate (KPAB) has been studied as a possible treatment for scleroderma, with mixed results. Further high-quality research is needed to determine if PABA may be useful in the treatment of this condition.
PABA is well-known as a part of sunscreen products used for the skin. However, there are few studies on its effectiveness for sun protection. The use of PABA in sunscreen has been reduced due to the reportedly high risk of allergic reactions and cross-sensitivity with other medications. Further studies may help to better understand the sun-protective benefits of PABA.
Early research is lacking to support the use of PABA for limb swelling. Although some research suggests that PABA may be effective, more studies are needed to make a firm conclusion.
* Key to grades
A: Strong scientific evidence for this use B: Good scientific evidence for this use C: Unclear scientific evidence for this use D: Fair scientific evidence for this use (it may not work) F: Strong scientific evidence against this use (it likley does not work)
Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. 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 healthcare provider. There may be other proposed uses that are not listed below.
Anesthetic (increase sensitivity to pain relief agents during surgery), anesthetic (applied to the skin for pain relief during surgery), anti-inflammatory, anti-malarial, antioxidant, blood thinner, chemotherapy side effects, chemotherapy support (increases effects of chemotherapy or radiation), clogged arteries, dental plaque, dermatomyositis (muscle disease that causes inflammation and skin rash), fertility, kidney stones, osteoarthritis, poisoning (with Paraquat, a toxic weed killer), retinopathy (damage to the retina of the eye), skin cancer prevention, vitiligo (loss of skin pigment causing white patches).
General: Several forms of PABA are available to be taken by mouth. These include: para-aminomethylbenzoic acid (PAMBA), butyl aminobenzoate (BAB), padimate O (octyl dimethyl PABA), potassium para-aminobenzoate (KPAB, POTABA®), N-benzoyl-L-tyrosyl PABA, and ursodeoxycholic acid-PABA. Since PABA is mostly eliminated by the kidneys, dosage adjustment may be needed in people who have problems with kidney function.
For asthma, one gram of PAMBA has been taken by mouth.
For cystoid macular edema (fluid build-up causing eye swelling), 75 milligrams of aminaphtone has been taken by mouth three times daily for one month.
For swelling, one tablet of aminaphtone has been taken by mouth every eight hours.
For hair color, PABA has been taken by mouth in doses of 6-48 grams daily for 1-27 months.
For Peyronie's disease, 12 grams of POTABA® has been taken by mouth daily with meals in four divided doses for 8-24 months.
For scleroderma, 8-12.5 grams of KPAB has been taken by mouth daily with meals for 1.25-26.6 months.
For eye pain and inflammation caused by the herpes virus, two drops of Aktipol® have been applied to the eyes 8-10 times daily.
For sun protection, 0.05 milliliters of 5 percent PABA in alcohol or a PABA emulsion plus oxybenzone has been applied to the skin, following a dose of 0.5 milligrams per kilogram of 8-methoxypsoralen taken by mouth.
For cancer-related pain, 10 percent BAB has been injected into the spine.
For pemphigus, to be used with standard treatment, 100-200 milligrams of PAMBA has been injected into the muscle daily for 7-26 days.
For cancer, 100 milligrams of PAMBA in combination with standard treatment has been placed into the bladder for two hours, once weekly for six weeks, then once monthly for up to two years.
Children (under 18 years old)
There is no proven safe or effective dose for PABA in children. However, some sources report that 220 milligrams per kilogram of PABA has been taken by mouth with meals in 4-6 divided doses.
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.
Avoid in people with known allergy or sensitivity to PABA and other forms of PABA.
Allergic skin reactions (including inflammation, itching, and rash) have been reported after applying PABA to the skin.
Side Effects and Warnings
PABA is likely safe when applied to the skin in concentrations of 1-15 percent in adults, either alone or combined with other agents in sunscreens.
PABA is possibly safe: when applied to the eyes as a 0.007 percent solution to treat pain and inflammation caused by herpes; when taken by mouth in doses of fewer than 8 grams daily in adults; when injected into the spine as 10 percent BAB in people with severe pain; and when injected into the muscle as up to 200 milligrams of PAMBA daily for up to 26 days as an additional treatment for pemphigus.
PABA may cause abnormal liver function tests, anxiety, chills, cold sweats, confusion, diarrhea, difficulty concentrating, fever, headaches, increased risk of autoimmune disease, increased sensitivity to light, jaundice (yellowing of the eyes and skin), liver toxicity, low white blood cell count, lung infection, nausea, problems with production of methemoglobin (a form of hemoglobin), rash, urinary problems (blood in the urine, frequency, pain during urination, or urgency), and vomiting.
PABA may lower blood sugar levels. Caution is advised in people with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
PABA may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
Use cautiously in people who have kidney disease, liver disorder, or urinary disorders.
Use cautiously when injecting PABA into the blood vessels.
Avoid in people with known allergy or sensitivity to PABA and other forms of PABA.
Avoid continuing the use of PABA after experiencing anorexia, nausea, rash, or upset stomach.
Avoid taking PABA by mouth in children, pregnant or breastfeeding women, and people who are taking sulfonamides.
Pregnancy and Breastfeeding
There is a lack of scientific evidence on the use of PABA during pregnancy or breastfeeding. Avoid taking by mouth in pregnant or breastfeeding women.
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, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal 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. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
PABA may also interact with agents for the blood, agents for the genital and urinary systems, agents for the lungs, agents for the nervous system, agents for the skin, agents for the stomach and intestines, agents that affect the immune system, agents that are applied to the skin, agents that are toxic to the liver, agents that increase sun sensitivity, agents that improve breathing, agents that improve digestion and stomach function, agents that protect against the sun, anesthetics, antacids, anticancer agents, antifolates, antihistamines, anti-inflammatories, antivirals, cortisone, cytotoxic agents, dapsone, digestive enzymes, estradiol, fibrotic disease agents, hormonal agents, interferon, methotrexate, para-phenylenediamine, pirenzipine, procaine-penicillin, procainamide, sulfonamides, and tinidazole.
Interactions with Herbs and Dietary Supplements
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 herbs and supplements, antihistamines, anti-inflammatories, antioxidants, antivirals, cytotoxic herbs and supplements, digestive enzymes, folic acid, herbs and supplements for the blood, herbs and supplements for the genital and urinary systems, herbs and supplements for the lungs, herbs and supplements for the nervous system, herbs and supplements for the skin, herbs and supplements for the stomach and intestines, herbs and supplements that affect cortisol levels, herbs and supplements that affect the immune system, herbs and supplements that are applied to the skin, herbs and supplements that are toxic to the liver, herbs and supplements that increase sun sensitivity, herbs and supplements that improve breathing, herbs and supplements that improve digestion and stomach function, herbs and supplements that protect against the sun, hormonal herbs and supplements, phytoestrogens, and probiotics.
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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.