Antibiotics can have side effects such as diarrhoea and feeling sick.

These side effects are usually mild and should pass once you finish your course of treatment.

If you get any additional side effects, contact your GP or the doctor in charge of your care for advice.

Rarely, some people may have an allergic reaction to antibiotics, especially penicillin and cephalosporins.

In most cases, the allergic reaction is mild to moderate and can take the form of:

• a raised, itchy skin rash (urticaria, or hives)
• coughing
• wheezing
• tightness of the throat, which can cause breathing difficulties

These mild to moderate allergic reactions can usually be successfully treated by taking antihistamines.

But if you're concerned, or your symptoms do not get better with treatment, call your GP for advice. If you cannot contact your GP, call NHS 111.

In rare cases, an antibiotic can cause a severe and potentially life-threatening allergic reaction known as anaphylaxis.

Call 999 or go to A&E now if:

• you have a skin rash that may include itchy, red, swollen, blistered or peeling skin
• you're wheezing
• you have tightness in your chest or throat
• you have trouble breathing or talking
• your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

Tetracyclines can make your skin sensitive to sunlight and artificial sources of light, such as sun lamps and sunbeds.

Avoid prolonged exposure to bright light while taking these medicines.

In very rare cases, fluoroquinolone antibiotics can cause disabling, long-lasting or permanent side effects affecting the joints, muscles and nervous system.

Stop taking fluoroquinolone treatment straight away and see your GP if you get a serious side effect including:

• tendon, muscle or joint pain – usually in the knee, elbow or shoulder
• tingling, numbness or pins and needles

Heart problems

Fluoroquinolone antibiotics can cause serious side effects in people who are at risk of heart valve problems.

Stop taking fluoroquinolone treatment straight away and see your GP if you get a serious side effect including:

• swollen ankles, feet and legs (oedema)
• new heart palpitations (heartbeats that suddenly become more noticeable)
• sudden shortness of breath

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine you're taking.

It's run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA).