Interactions with pharmaceuticals: none known.
Echinacea possibly interacts with cytochrome P450 3A4 (CYP3A4) substrates which, theoretically, may lead to an interaction with lovastatin, ketoconazole, fexofenadine, triazolam, and other drugs metabolized by CYP3A4.² Clinicians should monitor patients taking Echinacea with these drugs closely.

Echinacea may also reduce the effectiveness of immunosuppressive drugs (theoretically, not demonstrated clinically).⁵²

Interactions with other herbs: none known.