Though Ashwagandha is a widely used supplement and safe for most people, pregnant and breastfeeding women should avoid taking it as enough studies are not available to document its safety in pregnancy. People suffering from autoimmune diseases such as rheumatoid arthritis, lupus, etc. should also avoid Ashwagandha. People suffering from thyroid disorders should take it under medical guidance as it might increase the level of thyroid hormones in some.