The impact of H1N1 (swine) flu on the health service is becoming more severe. If you suspect you have caught it, the NHS recommends you stay at home to avoid infecting others.

How do you know if you have it?

The symptoms of swine flu are broadly the same as those of ordinary flu, the NHS advises, "but may be more severe and cause more serious complications". The sudden onset of a fever or cough is typical, as well as the traditional range of discomforts: headache, tiredness, chills, diarrhoea or stomach upset, loss of appetite, sneezing, and sore throat.

If you are concerned about your condition, what should you do?

Check your symptoms on the NHS Direct website. Call your local surgery and ask to speak to your GP. The doctor will prescribe antiviral medication, such as Tamiflu, if swine flu is diagnosed. Patients are still being asked to send a healthy friend along to pick up prescriptions from local pharmacies.

Who is most at risk of complications?

High-risk groups include people with long-term medical conditions, those aged over 65, young children and pregnant women. The earlier the antivirals are given the better. In severe infections, the virus affects the lungs, leading to the development of pneumonia. According to the Department of Health, "5-14-year-olds remain the age group predominantly affected".

How will the NHS cope? Trusts have been asked to focus their resources on coping with the pandemic. As the caseload grows, so the strains will increase – particularly in hotspot areas – at a time when more staff will be off sick.

Why have we changed from containment to treatment phase?

The government announced it had moved beyond the "containment" phase two weeks ago when the health secretary, Andy Burnham, warned that cases were doubling every week and the UK "could see over 100,000 cases per day by the end of August". At that point it stopped handing out precious Tamiflu tablets to those who might have been in contact with sufferers and decided only to prescribe anti-virals to those actually diagnosed as having swine flu – initiating the "treatment" phase.

What is most worrying about this pandemic?

The virus appears to be more contagious than normal seasonal flu, partly because pre-existing immunity is low. The continued high rate of spread at the height of summer was not anticipated. The first deaths of victims who had no apparent previous underlying health problems, suggest it can, in some cases, be extremely virulent.

What further precautions are being taken?

A major vaccine programme is now expected to begin as early next month, probably at the end of August. The public health debate may now focus on who is to be vaccinated first. The likely priorities are those deemed to be most at risk of suffering pneumonia, and frontline health and care workers. Meanwhile basic hygiene precautions for the public, including hand washing and disposal of tissues, are outlined on the official Directgov site direct.gov.uk/en/Swineflu

• This article was amended on Wednesday 15 July to add a link to Directgov.