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Strep A

Also called Group A streptococcus, GAS, or Invasive group A strep

Strep A (group A streptococcus) are bacteria that can cause many different infections. Most are mild, such as sore throats, tonsillitis, scarlet fever and skin infections like impetigo. Rarely, the bacteria get into the blood or deep tissues and cause serious illness, called invasive group A strep. It spreads through close contact, coughs and sneezes.

Last updated Nov 9, 2026

What it is

Most strep A infections are treated with antibiotics and get better quickly.

Invasive infections need urgent hospital treatment. Washing hands well and covering coughs help stop it spreading.

Common signs

  • A sore throat and high temperature
  • Swollen glands
  • A rash or skin sores
  • Muscle aches
  • Feeling or being sick

How it is usually diagnosed

  • Examination
  • A throat or skin swab
  • Blood tests if a serious infection is suspected

Records worth keeping

Keeping these together makes each appointment easier, especially when you see a new doctor:

  • Swab results
  • GP or hospital notes
  • Prescriptions

Questions to ask your doctor

  • Does this need antibiotics?
  • How long is it infectious?
  • Which warning signs should I watch for?

When to get help right away

Call 112 or go to the nearest emergency department if you have:

  • Difficulty breathing, a rash that does not fade with a glass, severe muscle pain, confusion, or a child who is very unwell: call 112

This page is general information. It is not a diagnosis and does not replace a doctor who knows your history. Medfold keeps your records organised; it does not interpret them.

Sources

Related conditions

Scarlet feverA bacterial infection, mostly in young children, that causes a sore throat, fever and a rough rash. It is treated with antibiotics.TonsillitisInfection of the tonsils at the back of the throat, usually caused by a virus. It is common in children and usually gets better in a week.ImpetigoA common, contagious skin infection causing sores that burst and leave golden crusts. It is usually treated with a cream.CellulitisA bacterial infection of the deeper layers of the skin that makes it red, hot, swollen and painful. It needs antibiotics.