Overview

Comfrey is made from the roots of a group of plants called Symphytum. It is commonly applied to the skin to help with minor bruises, sprains, and strains. However, its benefits for these uses are not well defined. Comfrey seems to be well tolerated when applied to the skin, but taking it by mouth can cause serious side effects, including liver damage. Before using comfrey, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is comfrey used for?

Comfrey is commonly applied to the skin for minor sprains, strains, and bruises, but its benefits are not well defined.

Taking comfrey by mouth can cause serious health problems and is not recommended.

Note: Comfrey is available in products that are applied to the skin. The FDA has not reviewed these products for safety and effectiveness. Learn more about cosmetics here.

How does comfrey work (mechanism of action)?

Comfrey is made from the roots of plants in the Symphytum genus. It is available in many products that are applied to the skin, including salves, creams, and ointments. Some of the chemicals in comfrey are thought to reduce swelling (inflammation). But it is not clear if comfrey can help manage symptoms of minor sprains, strains, or bruises. The benefits of comfrey for any use are not well defined.

Comfrey products may contain chemicals called pyrrolizidine alkaloids (PAs) that can be toxic when taken by mouth. To reduce the risk of serious health problems, many countries only allow comfrey to be added to products that are applied to the skin. See Warnings & Precautions for more information.

Herbal products, like comfrey, naturally contain many different chemicals. The amounts of each chemical in a specific comfrey product may vary. Some, none, or all of these chemicals may have effects on the body. These effects may change depending on how much of each chemical is found in the product you are using.

How should I store comfrey?

You should store comfrey 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 comfrey?

Comfrey seems to be well tolerated when applied to intact skin, according to product labeling. But taking comfrey by mouth can cause liver damage (see below). Tell your health care provider if you have any side effects that bother you.

There may be other side effects of comfrey 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 comfrey?

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

Severe Allergic Reactions. Comfrey may cause allergic reactions, which can be serious. Stop using comfrey 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

Liver Damage.Comfrey contains chemicals called pyrrolizidine alkaloids (PAs) that can cause liver damage (hepatotoxicity). This can happen when comfrey is taken by mouth or when large amounts of comfrey are applied to broken or damaged skin. However, it is usually safe when comfrey is applied to intact skin in small amounts as directed on the product label. Call your health care provider right away if you have any of the following symptoms of liver damage.

• Nausea or vomiting
• Stomach or belly pain
• Fever
• Weakness or unusual tiredness
• Itching
• Loss of appetite
• Light-colored poop
• Dark-colored urine (pee)
• Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Precautions

Who should not use comfrey?

Allergies to Ingredients. People who are allergic to any of the following should not use comfrey.

• Comfrey
• Symphytum
• Any of the ingredients in the specific product

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

What should I know about comfrey before using it?

Comfrey is available in products that are applied to the skin, including salves, creams, lip balms, and ointments. Do not apply comfrey to broken or damaged skin. If you get comfrey in your eyes, wash them right away with water. If your symptoms get worse while using comfrey, stop using it and speak to a health care provider. Read and follow the directions on the specific product you are using, or use it as recommended by your health care provider.

Comfrey products cannot be marketed to treat or cure a disease, and the FDA has not tested these products to confirm that they contain the ingredients stated on their labels.

Keep comfrey out of the reach of children. Children may be at increased risk for serious side effects from comfrey. Speak with your health care provider about the possible risks to your child.

Comfrey contains chemicals known as pyrrolizidine alkaloids (PAs). These chemicals can cause serious health problems when taken by mouth. Many countries, including the U.S., allow comfrey only in products that are applied to the skin. Applying comfrey to intact skin is unlikely to cause serious health problems. But applying comfrey to broken or damaged skin may increase the amount of comfrey absorbed by the body, increasing the risk of side effects. Do not take comfrey by mouth. If you are applying comfrey to the skin, read the product label closely and do not apply more than recommended.

Herbal products, such as comfrey, naturally contain many different chemicals. The amount of each chemical in a specific comfrey product can change for many reasons, including the area where the plant was grown, the weather during growth, the time of year it was harvested, and the way it was processed after being harvested. If you switch to a new bottle or a different brand, you may not have the same effects or side effects because of this variability. Talk to your health care provider if you have questions or concerns.

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

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. This will help them know if comfrey is right for you.

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

Pregnancy. There is some concern that comfrey could cause harm to a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if comfrey passes into breast milk. But comfrey can cause harm to an infant or a small child. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does comfrey interact with foods or drinks?

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

It is unknown if drinking alcohol will affect comfrey.

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

Dosing

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

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

Comfrey is available in many products that are applied to the skin. Read the product label closely and speak to a health care provider about how to use comfrey safely. Do not use more than recommended on the label.