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Overview: Ergothioneine is a substance that is naturally found in mushrooms and certain plants. Some people take ergothioneine supplements to reduce the effects of aging or improve their energy levels. But its side effects and benefits are not well understood. Before taking ergothioneine, tell your health care provider about all of your health conditions, including mushroom or mold allergies, and any medicines or supplements you may be using.

Uses

What is ergothioneine used for?

Ergothioneine supplements are used to reduce the effects of aging and increase energy levels, but their benefits are not well defined.

Note: The FDA has not reviewed ergothioneine for safety and effectiveness. Learn more about dietary supplements here.

How does ergothioneine work (mechanism of action)?

Ergothioneine is a type of chemical found in the diet. The highest amount of ergothioneine is found in mushrooms. Certain types of beans and some vegetables may also contain small amounts of this chemical.

Ergothioneine is a type of amino acid. Unlike most amino acids, your body does not use it to build protein. In fact, your body does not need ergothioneine to function. Although there is interest in using it as an antioxidant and to slow down aging, its effects are not well understood. More research is needed to see what benefits, if any, it may have in the body.

How should I store ergothioneine?

You should store ergothioneine according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of ergothioneine?

Ergothioneine seems to be well tolerated. But there isn’t enough research to know what the common side effects may be. Tell your health care provider if you have any side effects that bother you.

There may be side effects of ergothioneine that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of ergothioneine?

While less common, the most serious side effects of ergothioneine are described below, along with what to do if they happen.

Severe Allergic Reactions. Ergothioneine may cause allergic reactions, which can be serious. Stop taking ergothioneine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use ergothioneine?

Allergies to Ingredients. People who are allergic to any of the following should not take ergothioneine.

  • Ergothioneine
  • L-ergothioneine
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific ergothioneine products they stock.

What should I know about ergothioneine before using it?

Ergothioneine is a dietary supplement. It cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

Keep ergothioneine out of the reach of children.

If you are taking ergothioneine powder, use an appropriate measuring device to measure the powder, such as the device included with the product. Read the label carefully, and measure the amount stated on the label.

The FDA has not tested ergothioneine products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using ergothioneine?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. Also tell them if you have an upcoming surgery. Sharing this information will help your health care provider know if this or other supplements are right for you.

In particular, make sure that you discuss any of the following.

Allergies to Molds or Other Mushrooms. Many ergothioneine supplements are made from mushrooms or contain mushrooms. If you have had an allergic reaction to mold or mushrooms, you may be at a higher risk of having an allergic reaction to ergothioneine supplements. Speak to your health care provider before taking ergothioneine supplements if you have a mold or mushroom allergy.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Kidney problems
  • Liver problems

Pregnancy. It is not known if or how ergothioneine could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. Ergothioneine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does ergothioneine interact with foods or drinks?

There are no known interactions between ergothioneine and foods or drinks.

It is unknown if drinking alcohol will affect ergothioneine.

Does ergothioneine interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

The interactions between ergothioneine and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with ergothioneine is incomplete. Always check with your health care provider before taking ergothioneine with any medicines.

Overdose/Missed Dose

What should I do if I accidentally use too much ergothioneine?

If you or someone else has used too much ergothioneine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

Read the product label closely, and speak with a health care provider about how to take ergothioneine safely. Do not take double or extra doses, even if you miss a dose.