Most vaccines cause some mild side effects – that’s your immune system doing its job. Common reactions include soreness at the injection site, mild fever, tiredness, or body ache for a day or two. A cool compress and simple pain relief (if advised) usually handle these well.
Some people feel nothing at all, others feel like they’ve caught a small flu for a short time. Both responses can still mean the vaccine is working; the intensity of side effects doesn’t directly measure protection.
More serious side effects are rare, but it’s good to recognise warning signs. Difficulty breathing, swelling of the face or throat, severe rash, or chest pain soon after vaccination need urgent medical attention. Most centres observe you for a short period after the shot to catch immediate reactions.
If a mild fever or pain lasts beyond a few days, or you’re simply worried, it’s fine to contact a doctor or helpline and describe your symptoms. Sharing any past allergic reactions with the health team before getting vaccinated is also important.
Vaccines are one of the strongest tools in modern medicine, but understanding their effects calmly makes the experience less stressful.