If you are currently being treated with any of the following medications, you should not use hawthorn without first talking to your healthcare 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, this interaction has not been studied in people; therefore, the relevance of this interaction to people is unknown at this time.