Strep throat is an infection with a bacteria from the Streptococcus group. These are some of the most common disease-causing bacteria in humans.

Streptococci aren't always harmful - we all carry streptococcal bacteria in and on our bodies all the time, usually without knowing it. But one particular type of streptococci, known as haemolytic strep, does invade the tissues. It can cause infections such as strep throat, otitis media (middle ear infection), tonsillitis, pneumonia and wound infections.

One sub-type of haemolytic strep is responsible for scarlet fever, which can lead to rheumatic fever (which may damage the heart) and glomerulonephritis (a kidney disease). Fortunately, scarlet fever is rare in the UK and severe complications are even rarer due to the use of antibiotics.

Streptococcal infections used to be treated easily with penicillin. Now, however, they're growing increasingly resistant, so other antibiotics have to be used. Ideally, when a first course of antibiotics doesn't work, a different type of antibiotic should be given instead.

Rest is also important to allow your body to overcome the infection. Take things gently, get lots of sleep, fluid and healthy food, and you should soon be better.