COMFREY Overview Information
Comfrey is a plant. Even though this plant contains poisonous chemicals called pyrrolizidine alkaloids (PAs), the leaf, root, and root-like stem (rhizome) are used to make medicine. The amount of PAs found in comfrey changes according to the time of harvesting and the age of the plant. The roots have 10 times higher amounts of PAs than the leaves. Some products labeled “common comfrey” or Symphytum officinale actually contain the more poisonous “prickly comfrey” (Symphytum asperum) or “Russian comfrey” (Symphytum x uplandicum) species.
Comfrey is used as a tea for upset stomach, ulcers, heavy menstrual periods, diarrhea, bloody urine, persistent cough, painful breathing (pleuritis), bronchitis, cancer, and chest pain (angina). It is also used as a gargle for gum disease and sore throat.
Comfrey is applied to the skin for ulcers, wounds, joint inflammation, bruises, rheumatoid arthritis, swollen veins (phlebitis), gout, and fractures.
How does it work?
The chemicals in comfrey might have a healing effect and reduce inflammation when applied to the skin. However, comfrey contains toxic chemicals that can be absorbed through the skin.
COMFREY Uses & Effectiveness 
Insufficient Evidence for:
- Bruises and sprains when applied to the skin. Developing research suggests that applying comfrey directly to the skin might improve pain and tenderness of bruises, sprains, and painful conditions of the muscles and joints.
- Skin ulcers.
- Wounds.
- Broken bones.
- Heavy menstrual periods.
- Diarrhea.
- Cough.
- Sore throat.
- Gum disease.
- Joint pain.
- Chest pain.
- Cancer.
- Inflammation (pain and swelling).
- Other conditions.
COMFREY Side Effects & Safety
Comfrey is LIKELY UNSAFE for anyone when taken by mouth. It contains chemicals (pyrrolizidine alkaloids, PAs), that can cause liver damage, lung damage, and cancer. The FDA has recommended removal of oral comfrey products from the market.
Comfrey seems to be safe for most people when applied to unbroken skin in small amounts for less than 10 days. It’s important to remember that the poisonous chemicals in comfrey can pass through the skin. Absorption of the chemicals increases if the skin is broken or if large amounts are applied.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Comfrey is LIKELY UNSAFE to take by mouth or apply to the skin if you are pregnant or breast-feeding. In addition to causing liver damage and possibly cancer, the PAs in comfrey might also cause birth defects. Even topical use is unwise, since the PAs can be absorbed through the skin.Broken or damaged skin: Don’t apply comfrey to broken or damaged skin. Doing so might exposure you to large amounts of the chemicals in comfrey that can cause liver damage and other serious health effects.
Liver disease: There is a concern that comfrey might make liver disease worse. Don’t use comfrey if you have any problems with your liver.
COMFREY Interactions
Major Interaction Do not take this combination
- Medications that can harm the liver (Hepatotoxic drugs) interacts with COMFREY
Comfrey might harm the liver. Taking comfrey along with medication that might also harm the liver can increase the risk of liver damage. Do not take comfrey if you are taking a medication that can harm the liver.
Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.
Moderate Interaction Be cautious with this combination
- Medications that increase the breakdown of other medications by the liver (Cytochrome P450 3A4 (CYP3A4) inducers) interacts with COMFREY
Comfrey is broken down by the liver. Some chemicals that form when the liver breaks down comfrey can be harmful. Medications that cause the liver to break down comfrey might enhance the toxic effects of chemicals contained in comfrey.
Some of these medicines include carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin), rifampin, rifabutin (Mycobutin), and others.
COMFREY Dosing
The appropriate dose of comfrey depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for comfrey. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.
