Cold, flu, COVID-19 or RSV: telling common respiratory viruses apart

All four viruses infect the nose, throat and chest, so the same few complaints recur: a runny or blocked nose, sore throat, cough, tiredness and sometimes a temperature. The NHS says directly that COVID-19 symptoms are very similar to those of other illnesses such as colds and flu, and that RSV mostly produces cold-like illness.

For that reason, the useful questions are practical ones: how fast did it start, how wiped out do you feel, is anyone in the home at higher risk, and are there any danger signs.

This table paraphrases the NHS descriptions of each illness. Real-life illness varies, and a single symptom cannot confirm the cause.

A cold centres on a blocked or runny nose, sneezing, sore throat, hoarse voice and cough, sometimes with a temperature, aching muscles, pressure in the ears and face, and occasionally loss of taste and smell. Flu adds a sudden high temperature, aching body, exhaustion, headache, dry cough and loss of appetite. In children the NHS also lists ear pain, sore eyes and swollen glands, and says they may seem less active.

Colds are spread by coughs and sneezes, and the germs can live on hands and surfaces for 24 hours. A person can pass one on from a few days before symptoms begin until they finish. The NHS suggests staying home with a high temperature or when too unwell for normal activities.

COVID-19 symptoms listed by the NHS include a high temperature, a new continuous cough, a loss or change in smell or taste, breathlessness, tiredness, aches, headache, sore throat, a blocked or runny nose, loss of appetite, diarrhoea and nausea. The NHS says most people no longer need a rapid test with symptoms, but anyone eligible for COVID-19 treatment should test as soon as symptoms start. Its published guidance for a positive test is to try to stay at home for 3 days after the test date for those under 18, 5 days for adults, and to avoid people more likely to become seriously ill for 10 days.

RSV usually causes a runny nose, cough, sneezing, tiredness and temperature, with babies irritable and feeding less. The risk is a chest infection. Fast breathing, wheezing, worsening cough, difficulty feeding and, in older adults, confusion may mean pneumonia or bronchiolitis has developed. There is no specific treatment; hospital care, when needed, is fluids and oxygen.

The NHS advice to call 999 or go to A&E includes severe breathing difficulty (gasping, unable to speak), sudden chest pain, coughing up blood, lips or skin turning pale, blue or grey, collapse or a first seizure, and a non-fading rash. In a baby, grunting, long pauses in breathing or the tummy sucking in under the ribs also count.

Urgent GP or NHS 111 advice is advised for worsening illness, much reduced feeding, signs of dehydration such as a dry nappy for 12 hours, a high temperature that does not settle, or any cold-like illness in someone with a long-term heart or lung condition or weakened immunity. Parents should also seek help for fever in very young babies at the thresholds the NHS gives.

Home care is similar for all four: rest, plenty of fluids, and paracetamol or ibuprofen for discomfort, never aspirin for under-16s. Saline drops help blocked noses in children, and a pharmacist can advise on cough and cold products, noting that some are unsuitable for babies, children and pregnant women. Do not combine multi-symptom products with paracetamol, which risks an overdose.

Prevention differs. Flu and COVID-19 vaccines are offered to eligible groups each season, an RSV vaccine is offered in pregnancy and to older adults, and good hygiene helps against all four. Staying away from newborns when you have a cold is specifically recommended.