Good news: Calendula is not known to have many adverse side effects. However, it is possible that this herb could cause an allergic reaction, especially in people with known allergies to marigolds or plants in the marigold family. Asteraceae Family. It may also interfere with certain medications, such as sedatives, blood pressure medications, or diabetes medications. If you are concerned, check with your doctor about possible contraindications before spending your money on calendula.
