A side effect is an unwanted effect of a medicine taken at a normal dose. Most are mild and settle as your body adjusts, but some are warning signs that need same-day or emergency care. This hub explains the difference, shows you what to record before you speak to a professional, and points you to the right guide for your medicine or symptom.
This page is general information for people in South Africa. It cannot tell you whether your medicine caused your symptom. Only a doctor or pharmacist who knows your history can do that.
Start here: find the right side-effect guide
Category cards
Pick the route that matches the question you actually have:
- You know the medicine. Start with the medicine side effects A to Z index and find it by name or brand.
- You know the symptom but not the cause. Use the side effect symptoms index to work backwards from what you are feeling.
- You are worried it is serious. Read serious medication side effects for the warning signs that need urgent attention.
- You want to check a combination. Try the side effects checker or the South African checker guide.
- You want to know what to do next. Go to what to do if a medicine causes side effects.
Common vs serious effects
The useful question is not whether a side effect is on the leaflet. Almost everything is on the leaflet. The useful question is whether the effect is tolerable and settling, or whether it is escalating, disabling, or involves breathing, circulation, the skin, or your mental state. That distinction is covered in more depth in what are medication side effects and in the comparison of side effects and adverse drug reactions.
Common side effects vs serious side effects
Common examples linked to medication side effects
Across very different medicine classes, a small group of effects comes up repeatedly because they reflect how the body handles a new substance rather than anything specific to one drug:
- Digestive. Nausea, loose stools, constipation, stomach discomfort. Often worst in the first days and often eased by taking the dose with food, where the leaflet allows it.
- Neurological. Headache, drowsiness, light-headedness on standing, difficulty sleeping.
- Skin. Mild itch or a flat rash, which needs a closer look because skin reactions sit on a spectrum from trivial to dangerous.
- Systemic. Tiredness, appetite change, dry mouth, altered taste.
For a fuller treatment of this group, see common medication side effects. If your question is how long to expect them to last, see how long medication side effects last, and for practical steps, how to manage medication side effects.
How to describe frequency without overclaiming
Patient leaflets group side effects by how often they were seen in studies, using bands such as very common, common, uncommon, rare and very rare. Those bands describe how often an effect was recorded in a trial population. They do not describe your personal risk, and they are not a ranking of severity. A rare effect can be an emergency and a very common one can be harmless.
The same caution applies to the word caused. Symptoms that start after a new medicine may be from the medicine, from an interaction, from the illness being treated, or from something unrelated. Working out which is a clinical judgement. What you can usefully do is record the timing accurately so someone qualified can make that call.
Medicine, supplement and symptom categories covered
Priority related pages
- Medicine allergic reaction symptoms and side effect or allergic reaction, for telling a predictable dose-related effect apart from an immune reaction.
- What an adverse drug reaction is, for the term used in reporting and pharmacovigilance.
- Long-term mental health medication side effects, where the balance of benefit and effect changes over months rather than days.
- Chronic pain medication side effects and arthritis medication side effects, for sustained anti-inflammatory or analgesic use.
- Chronic kidney disease medication side effects, where reduced clearance changes how ordinary doses behave.
- Medicine overdose symptoms, if the concern is a dose that was too high rather than a reaction to a normal dose.
How to choose the right next guide
If you are taking one medicine and one symptom appeared, the medicine page will be more useful than the symptom page. If you take several medicines, or a medicine plus supplements, start from the symptom instead, because the cause may be an interaction rather than any single product. If you are deciding whether to keep taking something, go straight to should I stop taking a medicine because of side effects, which explains why stopping some medicines abruptly carries its own risk.
When to speak to a doctor or pharmacist
Red-flag symptoms
Get emergency help immediately, before phoning anyone for advice, if you have:
- Difficulty breathing, wheeze, or a tight throat
- Swelling of the face, lips, tongue or throat
- Chest pain, collapse, or fainting
- A seizure, or sudden confusion or unresponsiveness
- A rash that blisters or peels, or sores in the mouth, eyes or genitals, particularly with fever
- Vomiting blood, or black tarry stools
- Thoughts of harming yourself
When to contact a doctor, pharmacist, or emergency service
Contact a professional the same day, without waiting, if you have yellowing of the eyes or skin, a marked reduction in how much you are passing urine, a fever with a new rash, unusual bruising or bleeding, or a fast or irregular heartbeat. Book an ordinary appointment for effects that are mild but persistent, that are stopping you taking the medicine as prescribed, or that have not settled in the timeframe the leaflet describes.
A pharmacist is often the fastest first contact in South Africa for questions about an over-the-counter product, a suspected interaction, or whether an effect is expected. See when to see a doctor about medication side effects for how to judge the urgency.
How side effects can be reported in South Africa
What information to record
- The product name, strength and dose form, exactly as printed on the box
- The batch number and expiry date, which are on the carton or strip
- When you started it, and when the symptom began relative to a dose
- What the symptom is, how severe, and whether it is improving or worsening
- Every other medicine, contraceptive, herbal product and supplement you take
- Relevant history: pregnancy, breastfeeding, kidney or liver conditions, previous drug reactions
Where reporting fits into medicine safety
Clinical trials are too small and too short to find effects that are uncommon or that take years to appear. Those are found after launch, from reports submitted by patients and health professionals. In South Africa, the South African Health Products Regulatory Authority (SAHPRA) runs that system, and members of the public can report directly rather than only through a clinician. Our guide to reporting side effects in South Africa sets out the routes and what each one asks for.
Reporting is not a complaint and does not require you to prove the medicine was responsible. A suspicion is enough. Reporting also does not replace getting treatment, so deal with the symptom first.
Most useful next pages
Priority related pages
- Serious medication side effects
- What to do if a medicine causes side effects
- Should I stop taking my medicine
- Side effect symptoms index and medicine side effects A to Z
- Report a side effect in South Africa
How to choose the right next guide
If the symptom is severe or worsening, stop reading and get medical help. If it is mild and you want to understand it, use the medicine or symptom index. If you have already decided to raise it with someone, spend the time on the record-keeping list above instead, because that is what makes the consultation useful.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.