Most side effects are mild and many fade within days. Some need a call to your doctor. A few are emergencies. Your drug's label, and especially its Medication Guide if it has one, says which signs matter for that medicine. Here's general guidance to help you sort them out. It doesn't replace advice from your own doctor or pharmacist.
Call 911 or get emergency help for
- Trouble breathing, or swelling of your face, lips, tongue or throat. These can be signs of a severe allergic reaction.
- Chest pain or pressure, or a very fast or irregular heartbeat with fainting.
- Signs of a stroke, such as sudden weakness or numbness on one side, a drooping face or trouble speaking.
- A seizure, or bleeding that won't stop.
- Thoughts of harming yourself. In the U.S., you can also call or text 988, the Suicide & Crisis Lifeline.
If you think someone has taken too much of a medicine, call Poison Help at 1-800-222-1222 in the U.S.
Call your doctor or pharmacist soon about
- A new rash, especially with fever, blisters, peeling skin or sores in your mouth.
- Unusual bruising or bleeding, or black or bloody stools.
- Yellowing of your skin or eyes, or dark urine.
- Watery or bloody diarrhea, even weeks after finishing an antibiotic.
- New mood changes, confusion or unusual urges.
- Any side effect your label tells you to report, or anything that worries you.
Often worth mentioning at your next visit
- Mild side effects that linger or bother you, like an upset stomach, headache or trouble sleeping.
- Side effects that make it hard to keep taking the medicine as prescribed. There may be another option.
Don't stop on your own
It can be tempting to quit a medicine that's causing side effects, but stopping some drugs suddenly is dangerous. Seizure medicines, some blood pressure medicines and many drugs for anxiety, sleep or depression need to be lowered gradually. Clonidine, for example, can cause a sharp rise in blood pressure if stopped abruptly. Call first, and your doctor can help you change course safely.
Keep a simple record
Write down what happened, when it started, the medicine and dose, and anything else you'd started recently. It makes the conversation with your doctor much easier. If the side effect is serious, you can also report it to the FDA.
Sources
This article is general information, not medical advice. Talk to your doctor or pharmacist about your own medicines.