Different people have different reactions to the same medication. The drug that induces a rash in one person, might not affect another at all. However, that doesn’t mean that the person with the rash necessarily has an allergy to that drug. All medicines potentially have side effects, but only about 5% to 10% of adverse reactions are allergy-related. Both allergic and non-allergic reactions can vary from mild to life-threatening.
It is essential to take all medicines exactly as prescribed. If you suspect that you are allergic to a medication you have been given, or if you experience any worrying side effects, speak to your doctor about it. Of course, if your symptoms are severe, seek immediate medical attention.