Common side effects of dietary supplements can include gastrointestinal discomfort, nausea, and allergic reactions. Depending on the specific supplement, individuals may also experience headaches, dizziness, or interactions with medications. Overconsumption of certain vitamins and minerals can lead to toxicity and adverse health effects, making it essential for users to follow recommended guidelines. Always consulting with a healthcare provider before starting any new supplement regimen can help individuals avoid harmful side effects and ensure they are making informed choices regarding their health.