Long COVID symptoms: what to look for, how it is assessed and what helps

Long COVID is not one symptom but a changing mix of them, and it can affect people who had only a mild infection. This guide sets out the symptoms the NHS describes, how long COVID is assessed in the UK, what helps day to day, and an honest account of the research on hyperbaric oxygen therapy.

What are the most common long COVID symptoms?

The NHS long COVID page says symptoms can be different for everyone. The most common are:

• feeling extremely tired (fatigue)
• shortness of breath
• joint pain and aching muscles
• problems with memory and concentration, often called brain fog

The NHS also lists a wider range of symptoms:

• a high temperature, cough, sore throat, or blocked or runny nose
• chest pain or tightness and noticeable heartbeats (palpitations)
• headaches, dizziness and vertigo
• difficulty sleeping
• changes to the senses, including vision problems, earache, ringing in the ears (tinnitus) and changes to smell or taste
• tummy pain, diarrhoea, feeling or being sick, weight loss and poor appetite
• pins and needles and aches in different parts of the body
• hair loss and skin rashes such as hives
• sudden confusion, especially in older people
• anxiety and depression

Symptoms may improve, or come and go, and new symptoms can appear. The NHS notes they may get worse with stress or after being more active. That delayed worsening after effort is one reason pacing matters so much.

When does ongoing COVID become long COVID?

Timing shapes how doctors describe it. The NHS says long COVID, sometimes called post-COVID syndrome, is when COVID-19 symptoms last longer than 12 weeks.

NICE guideline NG188, developed with SIGN and the Royal College of General Practitioners, uses two clinical terms:

• Ongoing symptomatic COVID-19: symptoms from 4 to 12 weeks after infection.
• Post-COVID-19 syndrome: symptoms that continue for more than 12 weeks and are not explained by another diagnosis.

NICE says "long COVID" is commonly used to cover both. It describes symptoms that often overlap, fluctuate and change over time, and that can affect any system in the body. Importantly, the likelihood of developing it is not considered to be linked to how severe the original infection was.

How is long COVID assessed in the UK?

Start with your GP. According to the NHS, a GP will ask about your symptoms and how long you have had them. You may have:

• blood pressure and heart rate checks
• blood tests
• tests of the oxygen level in your blood
• referral for other tests, such as an ECG or chest X-ray

A symptom diary can help you and your GP see what makes things better or worse.

NICE's investigations and referral recommendations say doctors should first rule out acute or life-threatening complications and other diagnoses. After that, a referral to an integrated multidisciplinary assessment service can be considered from 4 weeks after the infection began. NICE notes that many people improve on their own between 4 and 12 weeks and should be offered self-management support and monitoring during that time. People should not be excluded from referral because they never had a positive COVID test.

In England, these are usually called post-COVID services. NHS England guidance moved responsibility for commissioning them to local integrated care boards from April 2024, so what is available varies by area. Services in Wales are organised by local health boards, so ask your GP what is offered where you live.

When should you get urgent help?

Not every new symptom is long COVID. NICE advises urgent referral to acute services when symptoms could point to a serious complication, including:

• low oxygen levels, or oxygen levels that drop on exertion
• signs of severe lung disease
• chest pain that could come from the heart

NICE also advises urgent psychiatric assessment for anyone with severe psychiatric symptoms or at high risk of self-harm or suicide. If symptoms like these come on suddenly or feel severe, seek urgent medical help rather than waiting for a routine appointment.

What helps with long COVID symptoms?

The NHS is clear there is currently no cure for long COVID, but treatments can help ease symptoms. Care is usually shared by a team of health professionals and may include:

• advice on how to manage fatigue
• physiotherapy and exercises for breathing and muscle pain
• cognitive behavioural therapy (CBT) for anxiety, depression and fatigue
• cognitive rehabilitation for memory, concentration and thinking
• help with smell, diet and nutrition
• social prescribing for practical, emotional and social support

Things you can do yourself, according to the NHS:

• set recovery goals with your care team
• keep a diary of symptoms and triggers
• go to sleep and wake up at the same time each day
• move regularly or take short walks if you can, but stop if symptoms appear
• talk to a GP and your employer if work is difficult

The NHS advises not to start exercising again before talking to a GP or specialist. NICE adds that it is not known whether over-the-counter vitamins and supplements help, harm or make no difference, and that a phased return to work or education can help.

Does hyperbaric oxygen therapy help long COVID?

Hyperbaric oxygen therapy (HBOT) means breathing concentrated oxygen in a pressurised chamber; our page on what HBOT is explains the mechanism. For long COVID the evidence is contested, and two substantial 2025 studies point in different directions.

A controlled trial found no benefit over sham. HOT-LoCO was a randomised, placebo-controlled, double-blind phase II trial at Karolinska University Hospital in Stockholm, published in BMJ Open. It enrolled 80 adults, who had 10 sessions of 100% oxygen at 2.4 bar for 90 minutes, or a sham treatment, over 6 weeks. At 13 weeks both groups had improved, with no significant difference between them in physical functioning or role limitations. The authors concluded that 10 sessions did not show more short-term benefit than placebo. Our summary of the HOT-LoCO trial covers it in more detail.

An uncontrolled registry reported improvement. A prospective registry in Scientific Reports followed 232 people treated at six Dutch hyperbaric centres. The standard protocol was 40 sessions at 2.4 to 2.5 ATA, lasting 90 to 110 minutes, five days a week for 8 weeks. At 3 months, median SF-36 mental scores rose from 45.5 to 57.0 and physical scores from 36.9 to 42.5.

That registry needs reading with its limits beside it:

• There was no control or sham group. The authors write that a causal effect of HBOT on the outcomes cannot be established.
• A minority of patients reported a significant and relevant deterioration after treatment.
• Fifteen people stopped early, ten because treatment was too exhausting or worsened their symptoms.
• Four authors were employed by the commercial hyperbaric providers that delivered the treatment, though they declared no ownership or shares.

What this adds up to. The evidence is contested, and no controlled trial has established that HBOT is an effective treatment for long COVID. HBOT is not among the long COVID treatments the NHS describes. Both studies used much higher pressure than our chamber, which runs at 1.5 ATA, so neither result can be assumed to apply to it.

In 2023 the Advertising Standards Authority upheld a complaint against a clinic that said HBOT helped recovery from long COVID, and told it not to claim HBOT could treat long COVID or its symptoms without adequate evidence. Treat any confident promise you see with care.

If you are thinking about HBOT anyway, read what happens in a session and who HBOT is not suitable for first, and agree with your own clinicians how you would judge whether anything has changed.

The practical takeaway

Long COVID symptoms are varied, can fluctuate, and deserve proper assessment rather than guesswork. Start with your GP, rule out other causes, use pacing and a symptom diary, and ask about your local post-COVID service. Keep your established care in place whatever else you consider.

If you would like to discuss HBOT after that, you can book a first appointment: no referral needed, and a medical consultation is included.