What Is Comfrey Cream?

Comfrey cream combines ingredients like oils or water and glyceryl stearate with Symphytum officinale (comfrey) extracts. Comfrey is an herb in the Boraginaceae family and has small purple flowers. It's found in Europe, Asia, and North America.

Comfrey cream contains several active components (substances). These include allantoin, rosmarinic acid, and others. Some of these components are thought to speed up wound healing by stimulating new cell growth.

Comfrey can also contain echimidine, pyrrolizidine alkaloids (PAs), and symphytine, which can damage the liver, are carcinogenic (cancer-causing) and may harm a fetus.

This article discusses the uses and benefits of comfrey cream. It also covers side effects, interactions, and what to look for.

Uses of Comfrey Cream

Comfrey has been used medicinally for at least 2,000 years for various conditions, including bone fractures, ulcers, and gout.

Researchers have investigated the effects of comfrey cream on several health conditions. However, further, well-designed studies are needed. Here's a look at research on comfrey cream for back pain, osteoarthritis, and ankle sprains.

Back Pain

One study in 120 patients with acute upper- or low-back pain used either 4 grams (g) of comfrey root ointment or a placebo (sham treatment) three times daily for five days. Study results revealed that pain intensity during active movement decreased an average of 95.2% in the group given comfrey ointment. This was compared to 37.8% in the placebo group.

Further study is needed to confirm these results.

Osteoarthritis

Comfrey cream may help treat knee osteoarthritis, according to a Cochrane review of topical herbal therapies. The review included one study of 220 people with knee osteoarthritis, a degenerative wear-and-tear joint condition. The participants were assigned three weeks of treatment with 2 g of either comfrey ointment or a placebo three times a day. Those who used the comfrey ointment experienced improvements in pain, mobility, and quality of life.

Another study found that comfrey ointment was superior to placebo in relieving pain and stiffness in osteoarthritis. The study involved 43 patients with knee osteoarthritis and a six-week treatment period.

A later study of 133 people found some evidence that a topical combination of comfrey extract and tannic acid led to reduced knee pain. However, it did not affect markers of inflammation or cartilage breakdown over 12 weeks of treatment. Using a combination product makes it challenging to know how much of the beneficial effect came from comfrey alone.

Ankle Sprains

A few studies show that comfrey cream may be helpful in the treatment of ankle sprains.

One study followed 142 patients with ankle sprains. One group used a cream with comfrey root fluid extract on the ankle while the others received a placebo. After eight days, the group that used the cream had significantly less pain than those who used the placebo.

In another study, participants with ankle sprains received either comfrey root extract cream or diclofenac gel, a nonsteroidal anti-inflammatory drug (NSAID). The ankle swelling decreased by 79.5% in the comfrey root group and 69.4% in the diclofenac group.

Additional Uses

Comfrey has also been used for the following conditions:

• Bruises
• Burns
• Fractures
• Gout (a form of arthritis)
• Rheumatoid arthritis
• Wounds

There is currently not enough evidence to recommend comfrey cream for any of these uses.

What Are the Side Effects of Comfrey Cream?

Using a supplement like comfrey may have potential side effects. These side effects may be common or severe.

Common Side Effects

A review of 26 clinical trials concluded that mild skin reactions were the most common side effects of comfrey creams used in the studies.

Severe Side Effects

Comfrey contains PAs, substances that can cause significant damage, including:

• Liver damage
• Sinusoidal obstruction syndrome (blockage of veins in the liver)
• Cancer
• Fetal harm (teratogen)
• Death

Therefore, it should never be taken by mouth. In 2001, the FDA banned oral comfrey products.

Since these toxic substances can be absorbed through the skin, there's concern about the safety of comfrey cream applied topically. It's typically only used in small amounts for a very short period.

Experts suggest not using comfrey cream for longer than 10 days in a row. Using it no more than four to six weeks a year as a general guideline would be best.

If you're considering using the cream, consult your healthcare provider first. You and your healthcare provider should weigh the pros and cons and use it only under their supervision.

Precautions

To reduce the risk of side effects, never apply comfrey cream to broken skin or open wounds as it may be more highly absorbed by the body.

Don't use comfrey products if you have or are at risk of having liver disease, cancer, or are taking any medication that affects the liver since it may increase the risk of liver toxicity.

Comfrey is not recommended for children under 3 years old, as it's not been studied in that population.

Comfrey shouldn't be used in any form during pregnancy or nursing due to the risk of liver damage to infants.

Dosage: How Much Comfrey Cream Should I Use? 

There is no daily recommended allowance for comfrey, sold in creams, ointments, gels, and salves. The following applications have been used in research:

• Back pain: An ointment containing 35% comfrey root extract, with or without 1.2% methyl nicotinate, applied three times a day for five days
• Osteoarthritis: A specific ointment containing 35% comfrey root extract, with or without tannic acid, aloe vera gel, eucalyptus oil, and frankincense oil; applied to the knee three times a day for three to six weeks
• For sprains: An ointment containing 35% comfrey extract; applied to ankle sprains four times daily for eight days

What Happens If I Use Too Much Comfrey Cream?

Using large amounts of comfrey cream or using it for extended periods of time increases the risk of side effects like liver toxicity.

Interactions

Because of the risk of liver toxicity, comfrey cream shouldn't be used with other medicines that may also cause liver damage.

The most common over-the-counter medication that can be toxic to the liver is Tylenol (acetaminophen). Other prescription medicines that may harm the liver include:

• Birth control pills
• Antibiotics like erythromycin, tetracycline, or amoxicillin-clavulanate
• Some anti-seizure medicines
• Methotrexate
• Cholesterol-lowering medicines like statins

Some supplements may also harm the liver, including:

• Green tea extract
• Ginseng
• Black cohosh
• Niacin
• Kratom
• Kava
• Supplements marketed for bodybuilding (e.g., anabolic steroids), weight loss, and sexual performance due to increased risk of adulteration (unknown, possibly dangerous chemicals added)

It is essential to carefully read a supplement's ingredients list and nutrition facts panel to learn which ingredients are in the product and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How to Store Comfrey Cream

Store comfrey cream according to package instructions, typically at room temperature (between 68 and 77 degrees F) and out of reach of children and pets. Discard after a year or according to labeling.

Similar Supplements

Other herbal supplements that may have benefits for back pain include:

• Cayenne
• Devil's claw
• White willow bark
• Lavender
• Magnesium
• Calcium/Vitamin D

Some other supplements that may be useful for osteoarthritis are:

• Glucosamine
• Chondroitin
• Ginger

Sources of Comfrey & What to Look For 

Comfrey may be used topically as a cream, ointment, salve, or paste. Avoid taking comfrey orally (by mouth).

Food Sources of Comfrey

Some people ingest comfrey roots or leaves or use them in teas. This is not recommended due to the presence of chemicals that can cause organ damage and cancer.

Comfrey Supplements

For topical comfrey cream, look for products labeled as free of pyrrolizidine alkaloids. These have a lower risk of serious side effects like liver damage.

When selecting a brand of supplements, look for products certified by ConsumerLab, USP, or NSF. These third-party organizations test products to ensure they were manufactured safely and contain the ingredients indicated on the labeling without contaminants.

Summary

Comfrey cream, a topical herbal product, is thought to reduce inflammation and pain when applied to the skin. Researchers have found it does seem to reduce pain in some conditions, including back pain, osteoarthritis, and ankle sprains.

However, comfrey can also contain toxic substances called pyrrolizidine alkaloids that cause liver damage, cancer, and death. You should never ingest comfrey by mouth. Consult your healthcare provider before using comfrey cream.