If you are taking prescription or non-prescription medicines, talk to your health care provider before taking herbal supplements. If you are currently being treated with any of the following medications, you should not use hawthorn without first talking to your health care provider:

Digoxin -- Hawthorn may enhance the activity of digoxin, a medication used for irregular heart rhythms.

Phenylephrine -- In a laboratory study, an alcoholic extract of hawthorn fruit counteracted the effects of phenylephrine, a medication that constricts blood vessels and is commonly found in nasal decongestant products. However, since this interaction has not been studied in humans, the relevance of this interaction to people is unknown at this time.