Comfrey is a perennial plant in the Boraginaceae family.1 It grows in lush areas such as along rivers and in ditches.1 The plant is native to Europe and features black turnip-like roots, broad leaves with bristles, and bell-shaped flowers that can be white, pink, or purple.1 Both the roots and the leaves of the comfrey plant have been used in herbal medicine.2 Comfrey should not be taken orally; instead, comfrey leaf uses include using them in ointments and creams to be applied topically and treat conditions like fractures, bruises, strains, sprains, pulled muscles, and osteoarthritis.3
Comfrey leaves come with numerous benefits. They contain a substance called allantoin, which helps promote new skin growth.3 The leaves also have anti-inflammatory properties.3 Products containing comfrey leaves can be applied topically to affected areas to help with the following conditions:
Comfrey is considered safe when applied topically according to the package directions. However, the plant contains substances called pyrrolizidine alkaloids, which are toxic and can damage the liver when taken orally.3 New leaves contain more pyrrolizidine alkaloids than old leaves, and the roots have up to 16 times more pyrrolizidine alkaloids in them.3 Because comfrey leaves contain this substance, you should avoid eating them. If you have a condition that might benefit from taking comfrey leaves orally, consult your doctor before doing so. It’s important to note that pyrrolizidine alkaloids can also be absorbed through the skin.3 For this reason, you should not apply comfrey lotions or ointments to broken skin. Follow the dosage recommendations on the product you’re using. Don’t use comfrey products for more than 10 days at a time or for more than six weeks in a calendar year.3 Do not use comfrey products if you have cancer, alcoholism, or liver disease.3 Pregnant and breastfeeding mothers, children, and the elderly should avoid using comfrey.3
Possible comfrey leaves side effects may include allergic reaction, such as hives, difficulty breathing, or swelling.6 Consult your healthcare provider if you experience nausea, tiredness, loss of appetite, upper stomach pain, dark urine, or jaundice (yellowing of the eyes or skin) as these may be signs of serious liver problems.6 Talk to your doctor to see if a comfrey herbal ointment is right for you.