If someone has difficulty breathing, swelling of the face or throat, chest pain, has collapsed, or is having a seizure, call emergency services or go to the nearest emergency unit now. Do not read further and do not wait to see whether it settles.
This page is for deciding quickly whether a medicine reaction is urgent, and what to do while help is on the way.
Common side effects and what they may feel like
Common examples linked to urgent medication side effects
Most reactions are not urgent. Nausea, headache, drowsiness, dizziness and digestive upset are unpleasant but rarely emergencies, and they are covered in common medication side effects.
What separates an urgent reaction is usually speed and system. Reactions that escalate over minutes, or that involve breathing, circulation, consciousness or widespread skin, are the ones that need immediate care.
How to describe frequency without overclaiming
Urgent reactions are uncommon, and that is a statement about likelihood beforehand, not about what to do once symptoms appear. Rarity is never a reason to wait.
Serious side effects and red flags
Red-flag symptoms
Emergency, immediately:
- Difficulty breathing, wheeze, or a tightening throat
- Swelling of the face, lips, tongue or throat
- Chest pain, fainting or collapse
- Seizure, or sudden confusion or unresponsiveness
- A rash that blisters or peels, or sores in the mouth or eyes with fever
- Vomiting blood, or black tarry stools
- Thoughts of harming yourself
Also treat as an emergency any suspected overdose, whether or not the person feels unwell, and any reaction in someone who is drowsy, confused or difficult to rouse.
Same day, not next week:
- Yellowing of the eyes or skin, dark urine, or pale stools
- Passing much less urine than usual, or marked swelling of the legs
- Fever with a new rash, or fever with mouth ulcers
- Unexplained bruising, or bleeding that is new for you
- A fast, slow or irregular heartbeat that is new
- Severe or worsening abdominal pain
- New muscle pain with weakness, or unusually dark urine
When to contact a doctor, pharmacist, or emergency service
While waiting for help: stay with the person, keep them sitting up if breathing is difficult, and do not give anything to eat or drink if they are drowsy or confused. Do not try to make anyone vomit. If they carry an adrenaline auto-injector for known allergies, use it as they have been trained to and still call for emergency help.
Take the medicine packaging with you, or photograph the carton including the batch number. Knowing exactly what was taken, how much and when saves time on arrival.
Risk factors, interactions and who should be cautious
People who may need extra caution
- Older adults. Slower clearance and more medicines at once. See side effects in older adults.
- Kidney or liver conditions. Reduced clearance means an ordinary dose can behave like a larger one.
- Pregnancy and breastfeeding. Ask before starting or stopping anything, including supplements.
- Children. Dosing is by weight and some medicines are unsuitable. See children and over-the-counter medicines.
- People taking several products. Risk rises with the number taken, including anything bought without a prescription.
- Anyone with a previous drug reaction. A past reaction can indicate risk with related medicines.
Medicine and supplement interactions to check
- Supplements with prescription medicines, including St John’s Wort
- Supplements with blood thinners
- Over-the-counter medicines alongside chronic medication
- Two products that both contain paracetamol
- Alcohol with chronic medication
What to do if you think this is a side effect
Common effects
If nothing on the urgent lists applies, use what to do if a medicine causes side effects instead.
Serious effects
Get help first. Report afterwards, once the person is safe, through the South African reporting routes. Serious reactions are the reports regulators most need.
When to speak to a doctor or pharmacist
Red-flag symptoms
When you are uncertain whether something is urgent, treat it as urgent. Being assessed and sent home is a good outcome.
When to contact a doctor, pharmacist, or emergency service
Emergency services for anything on the first list. A doctor the same day for the second. A pharmacist for everything else.
Related side-effect guides
Common effects
- Medication side effects hub
- Serious medication side effects
- What to do if a medicine causes side effects
- Side effect symptoms index
- Report a side effect in South Africa
Serious effects
See anaphylaxis from medicine and overdose symptoms.
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.