Streptococcus A (strep A)

Group A Streptococcus (GAS), also known as Strep A, are bacteria commonly found on the skin or in the throat. Under some circumstances these bacteria can cause disease.

GAS infection commonly presents as a mild sore throat ('strep throat') and skin/soft tissue infections such as impetigo and cellulitis.

Immediate action required: Phone 999 or go to A&E if:

  • you or your child is having difficulty breathing (you may notice grunting noises or their tummy sucking under their ribs)
  • there are pauses when you or your child breathes
  • you or your child's skin, tongue or lips are blue
  • you or your child is floppy and will not wake up or stay awake

Urgent advice: Contact your GP if you or your child:

  • is getting worse
  • is feeding or eating much less than normal
  • is showing signs of dehydration, like sunken eyes, drowsiness
  • has not passed urine for 12 hours
  • is under 3 months and has a temperature of 38°C
  • is older than 3 months and has a temperature of 39°C or higher
  • feels hotter than usual when you touch their back or chest, or feels sweaty
  • is very tired or irritable

If your GP is closed, phone the 111 service.

If you feel that you or your child is seriously unwell, trust your own judgement and seek medical assistance.

Strep A tests are not available through the NHS in Scotland for self-testing at home. Should you or your child need to be tested for Strep A, your GP or other healthcare professional will advise you.

GAS infections

GAS bacteria can cause a wide variety of skin, soft tissue and respiratory tract infections ranging in severity from mild to life-threatening. These include:

In rare cases, patients may go on to develop post-streptococcal complications, such as:

  • rheumatic fever
  • glomerulonephritis (heart and kidney diseases caused by an immune reaction to the bacteria)​

iGAS infections

GAS can very rarely cause more serious conditions, known as invasive group A Streptococcus (iGAS) infections. These can include:

  • bacteraemia (an infection of the bloodstream)
  • septic arthritis
  • meningitis
  • necrotising fasciitis (a severe infection involving death of areas of soft tissue below the skin)
  • Streptococcal toxic shock syndrome (rapidly progressive symptoms with low blood pressure and multi-organ failure)

iGAS infections tend to happen in the elderly, the very young, or people with an underlying risk factor such as injecting drug use, alcoholism, immunosuppression or cancer.

Treating GAS infections

Most GAS infections are relatively mild illnesses that clear up on their own without the need for antibiotics.

Often symptoms that look like GAS infections, like sore throats, are more commonly caused by viruses than GAS bacteria. If you or your child has a runny nose with their sore throat, it's likely to be a virus infection. Sore throats caused by viruses do not need to be treated with antibiotics unless there are concerns about complications.

More about sore throat symptoms, self-care at home, and what to do if your condition worsens 

Your healthcare professional will consider antibiotics if they think:

  • you or your child need medication to get better or to ease symptoms
  • you or your child are at risk of serious complications from a GAS infection
  • you or your child has scarlet fever

If you or your child is prescribed antibiotics, they could be in liquid or pill form.

It's not uncommon for someone to have GAS bacteria on their skin or in their throat without being unwell. These people often don't know they have the bacteria and won't need antibiotics.

Preventing GAS infection

GAS are spread by close contact between individuals, through respiratory droplets (moisture in your breath) and direct skin contact.

To help reduce the risk of picking up or spreading infections:


  • wash your hands properly with soap for 20 seconds
  • use a disposable tissue to catch coughs and sneezes and wash your hands afterwards
  • keep away from others if you feel unwell


  • do not share contaminated food, utensils, cups and glasses, baths, bed linen or towels

GAS can be a secondary infection, developing in people who are already unwell with illnesses like the flu. You can help protect your child from this risk by making sure they get their free flu vaccine this winter.

New evidence also shows that the nasal spray flu vaccine offered to children may also protect them from GAS infection. 

Last updated:
23 June 2023