Papain is a proteolytic enzyme extracted from the raw fruit of the papaya plant. Proteolytic enzymes help break proteins down into smaller protein fragments called peptides and amino acids. This is why papain is a popular ingredient in meat tenderizer.

You can get papain from eating raw papaya. Papain is also available in topical, chewable, and capsule forms. You can purchase papain-only supplements or supplements that pair papain with other enzymes, such as bromelain.

Papain is a popular folk remedy to reduce pain, inflammation, and swelling. It has also been used to improve digestion and to treat infections, diarrhea, and allergies. It’s also being studied for potential use in cancer and other diseases.

Read on to learn how to use papain for its health benefits, as well as some of the science-based evidence surrounding this enzyme.

Papain may help relieve sore throat symptoms, such as swelling, pain, and redness. According to very dated research on 100 people with pharyngitis or tonsillitis, throat lozenges containing 2 milligrams (mg) of papain, 5 mg of lysozyme, and 200 international units (IU) of bacitracin helped relieve sore throat symptoms better than a placebo.

It's not known if the beneficial effects are due to papain itself, the other ingredients, or the specific combination of ingredients. Recent scientific research is lacking, however.

How to use: While it’s not clear if papain will help, if you want to try it, chew a lozenge containing papain at the first sign of sore throat. Don’t exceed the manufacturer’s recommended dosage.

According to an article in Nutrition Review, research has shown proteolytic enzymes help reduce inflammation as well as or better than some anti-inflammatory drugs. However, clinical research in people is limited.

Because of these potential beneficial effects papain and other proteolytic enzymes are sometimes use to help with wound healing and to decrease swelling after an injury or trauma.

How to use: If you're interested in trying papain, talk with your doctor first. Your doctor can recommend the best approach for treating wounds, pain, or swelling after an injury or surgery. Papain supplements can interact with certain medications, so don’t skip consulting your doctor.

Papain may also ease digestive symptoms like constipation and bloating. According to one 2013 study, a whole papaya preparation called Caricol significantly improved constipation and bloating in people with chronic gastrointestinal dysfunction.

How to use: Caricol is available online in packet form. Add one packet to water or juice after meals, up to three times daily or as directed by your doctor.

Papain itself has been used for improving digestion, but there is no reliable evidence that it works for this use in people.

Research also suggests that papain may be used as a natural remedy for skin ulcers, wounds, and other skin conditions.

For example, a 2010 animal study found a papain-based wound cleanser helped promote wound healing in rats. A 2012 systematic review of studies also concluded papain is effective and safe in treating many types of wounds in various stages of healing. Most of the research is still preliminary.

Despite these positive findings, the U.S. Food and Drug Administration (FDA) ordered companies to stop marketing unapproved topical papain products due to some people experiencing a life-threatening allergic reaction upon use. You should talk with your doctor about your individual risk of allergic reaction before use.

How to use: Papain salves and creams are available online and in some natural health stores. Use as directed under your doctor’s supervision. If you've had an allergic reaction to papaya or latex, don't use these products. If you're not sure, talk with your doctor about doing a patch test.

To perform a patch test: Apply a small amount of product to your elbow or inner wrist. Cover with a bandage, and leave on at least 12 hours. If irritation occurs, rinse thoroughly and consult your doctor. Don’t use the product again.

Protease supplements may relieve muscle pain caused by intense exercise, according to a 2004 study. In this study, 10 matched pairs of male participants were given either a placebo or a protease supplement containing papain and other protease enzymes.

The treatment was given prior to and after downhill running for 30 minutes at 80 percent of their maximum heart rate. The enzyme group experienced better muscle recovery and less muscular pain than the placebo group.

How to use: Take a daily protease enzyme supplement that includes papain.

Proteolytic enzymes such as papain may help shingles symptoms such as pain, skin lesions, and neuralgia.

According to a 1995 controlled study of 192 people with shingles, a proteolytic enzyme preparation was as effective in treating shingles symptoms as the antiviral medication acyclovir. More current studies are lacking, however, and more evidence is needed to confirm these findings.

How to use: At the first sign of shingles, take papain supplements as directed by your doctor. But don’t treat shingles with papain without consulting your healthcare provider. Evidence is limited, and shingles can be serious. Talk to your doctor before you rely on papain or other proteolytic enzymes for this condition.

Papain supplements, or taking high doses of papain, may cause:

People who are allergic to latex or papaya shouldn’t use papain. Topical papain may cause allergic reaction, blisters, and skin irritation.

Papain may lower blood sugar. Use with caution if you have diabetes, hypoglycemia, or use medications or natural remedies that lower blood sugar.

Papain may increase your bleeding risk. Don’t use papain if you take blood thinners or have a blood clotting disorder. Stop taking papain two weeks prior to surgery.

Pregnant and breastfeeding women or women who are planning to become pregnant shouldn’t use papain supplements. There is potential for harm to the baby. As well, a 2002 animal study suggests that eating papaya may cause fetal poisoning or birth defects when consumed in large amounts.

Research suggests papain supplements may help digestion, relieve pain, and reduce inflammation. Even so, more study is needed to prove its effectiveness for most conditions.

Serious allergic reactions to papain are possible. Only purchase papain supplements from a trusted source.

Not all brands have the same amount of active ingredients. Not all supplements are manufactured using rigorous standards so it’s hard to know if you’re getting a high-quality, pure, safe product.

Talk to your doctor or other health practitioner before using papain to confirm the proper dose and to determine if it’s a safe option for you.