Like any form of plant medicine, ashwagandha does come with some potential side effects, particularly when consumed in large doses. Here are the most noteworthy ones to keep in mind: Upset stomach Diarrhea Vomiting Ashwagandha is not recommended for those who are pregnant or nursing. It may also interact negatively with certain medications, including the following: Those that lower blood sugar or blood pressure Those that suppress the immune system Those that act as sedatives Those that affect thyroid hormone levels If you’re concerned about how ashwagandha might interact with a medication you use, consult a physician before consuming it.