Adverse effect (medicine)

Adverse effects in medicine are like bad reactions to a medication or treatment. Sometimes when people take a medicine, it can sometimes make them feel worse, instead of better. It might make their bodies feel icky, or cause them to vomit or have a headache or an upset stomach. It's important to tell your doctor or nurse if you have these kinds of reactions so they can help you figure out what the problem is and make it better.