What should you know about systemic antibiotics?

Unlike a medicine applied only to the skin or eye, a systemic antibiotic is swallowed or given by injection and reaches tissues through the circulation. The choice depends on the suspected bacteria, infection site, allergies, kidney function and previous antibiotic use. Antibiotics do not work against viruses, so they are not a routine treatment for colds or flu. Some bacterial illnesses, including cellulitis and certain sexually transmitted infections such as chlamydia or gonorrhoea, may need systemic treatment. The medicine may cause nausea, loose stools, rash or other reactions, and unnecessary use can make future infections harder to treat.

Take each dose at the prescribed time and follow the instructions about food, fluids and missed doses. Complete the course unless the prescriber tells you to stop, and do not share leftover tablets or save them for another illness. Tell the clinician about an antibiotic allergy, pregnancy, long-term conditions and every medicine or supplement you use. Ask whether you should avoid alcohol or particular foods. Keep follow-up advice, especially when treatment is for a deeper infection such as brucellosis or Helicobacter Pylori Infection.

Contact a clinician promptly if symptoms are worsening, do not begin to improve as expected, or return after treatment. Seek urgent help for swelling of the lips or face, wheezing, trouble breathing, faintness or a widespread blistering rash after a dose. Severe or persistent diarrhoea, blood in the stool, repeated vomiting or inability to keep fluids down also needs medical advice. A new eye pain or change in vision with conjunctivitis should be assessed rather than treated with someone else’s medicine.

Ask which bacteria are being treated, how quickly improvement should begin, what to do if a dose is missed, and which warning signs require a review. You can also ask whether a sample or test is needed before changing treatment.