How to tell difference between covid, flu, RSV and common cold winter 2025

Spot these red flags to tell different common bugs and viruses apart this winter

As we approach the winter months, it’s crucial to be aware of the various illnesses that tend to circulate during this time of year. With a multitude of common winter bugs and viruses causing similar symptoms, it can often be challenging to distinguish between them.

Winter is a prime time for diseases to spread, as people spend more time indoors, creating a breeding ground for these common health issues. However, with such a wide range of problems that can look similar side-by-side, diagnosing the problem can sometimes feel like a guessing game.

But, common illnesses such as colds, flu, and RSV each have some clear traits that can help identify which virus is causing the problem. While these differences may be subtle, recognising the cause of the illness can potentially lead to a quicker recovery.

The UK Health Security Agency (UKHSA) has put out some information alongside the NHS in preparation for the winter season, a period when certain diseases are known to spread rapidly from one household to another. Although these viruses can circulate throughout the year, they tend to peak during the colder months.

Here, we outline the differences between COVID, the flu, the common cold and the respiratory syncytial virus (RSV), including the recognised symptoms of each, according to the Express.

Flu

Flu is a viral infection that affects the nose, throat, and lungs, most commonly during the winter months. It tends to feel significantly worse than a typical cold. Symptoms of the disease develop rapidly and can include:

• A sudden high temperature,
• an aching body,
• feeling tired or exhausted,
• a dry cough,
• a sore throat,
• a headache,
• difficulty sleeping,
• loss of appetite,
• diarrhoea or tummy pain,
• feeling sick and being sick.

Covid-19

Although Covid-19 is not as critical for the majority of people as it was during the initial phases of the pandemic, it still leads to significant illness, hospitalisations, and fatalities—particularly among people with compromised immune systems and those aged 75 and older. Many people experience symptoms similar to a typical cold, while others may additionally have:

• Fever or chills,
• a persistent cough,
• shortness of breath,
• fatigue,
• body aches,
• headaches,
• a sore throat,
• a blocked nose,
• loss of appetite,
• nausea,
• diarrhoea,
• or changes in taste or smell due to the latest variants.

As of October 2025, the predominant covid-19 strains circulating are the Omicron subvariants XFG, known as “Stratus,” and NB. 1.8.1, dubbed “Nimbus.” They have become the most prevalent variants circulating in the UK, as reported by officials.

These variants are being closely monitored by UK authorities and the World Health Organisation (WHO). The Stratus variant has been linked to a hoarse voice, although some experts question whether this is a reliable distinguishing symptom from other respiratory viruses.

The Nimbus variant is associated with a particularly severe or “razor blade” sore throat. Experts indicate that these variants do not seem to present a greater threat than earlier strains of covid, nor do they cause increased illness.

RSV

Respiratory syncytial virus (RSV) is a major respiratory virus that is common over the winter period, typically November to February, and can spread through coughs and sneezes. Almost all children get them at least once before they’re 2 years old.

While they’re typically not severe, certain babies and adults are at an increased risk of becoming seriously ill. Most individuals only experience symptoms akin to a common cold, but if these escalate into more serious infections, such as pneumonia or bronchiolitis, they can result in breathlessness and a worsening cough.

Rhinovirus/common cold

Better known as the common cold, symptoms gradually appear over two to three days. The main signs of this illness include a blocked or runny nose, sneezing, a sore throat, a hoarse voice, a cough, and feeling fatigued and unwell.

Symptoms of a cold can last longer in young children. They may also be irritable, have difficulty feeding and sleeping, breathe through their mouth, and get sick after coughing. You may also experience a high temperature, muscle aches, loss of taste and smell, and a feeling of pressure in your ears and face. Cough and cold medicines can be obtained from pharmacies or supermarkets.