As cases of coronavirus continue to rise around the world, there are some lesser known symptoms of the virus people should be on alert for.
The NHS only lists a high temperature, a persistent cough and a loss of taste or smell as official signs of Covid-19.
However, some people experience milder symptoms, which can be the only indications they are infected.
As the second wave continues to infect hundreds of people in Wales each day, here are some unofficial signs of the virus being highlighted by people who have tested positive.
1. Stomach ache
Some coronavirus patients have suffered stomach aches before developing other official symptoms, the Mirror reports.
The American Journal of Gastroenterology published a study suggesting the virus could cause digestive problems such as diarrhoea.
It analysed data from 204 patients in China, discovering that 48.5 per cent of them suffered stomach problems such as vomiting, abdominal pain or diarrhoea when they were first hospitalised.
Teenager Dar’yana Dyson, from Maryland, Baltimore, US, died from a coronavirus-related inflammatory condition after suffering an upset stomach alongside other symptoms.
The 15-year-old’s mum Kandace Knight told local news station WBAL-TV : “It happened so fast. I never thought that taking my daughter to the hospital for a stomach pain that I wouldn’t be walking out of there with her.
“She was so beautiful, she was too good for this world.”
Dr Diana Gall told the Express : “Digestion problems and changes in bowel habits – particularly looser stools and making more frequent trips to the toilet – are sometimes the first signs that you’re coming down with something, not just with this coronavirus.
“However, diarrhoea has been reported as an early symptom in patients who have later tested positive for Covid-19.”
2. Eye infection
Though not recognised as an official symptoms, eye infections are regarded by some doctors as another potential sign of Covid-19.
Conjunctivitis, also known as pink eye, develops in around 1% to 3% of patients, according to the American Academy of Ophthalmology.
Chelsey Earnest, a nurse at the Life Care Centre in Washington, told CNN that red eyes are the “single most important” sign that patients have Covid-19.
She said: “They have, like…allergy eyes. The white part of the eye is not red. It’s more like they have red eye shadow on the outside of their eyes.”
However, you shouldn’t panic at the first sign of a red eye.
The American Academy of Ophthalmology said: “It doesn’t mean that person is infected with coronavirus.
“But health officials believe viral pink eye, or conjunctivitis, develops in about 1% to 3% of people with coronavirus.
“The virus can spread by touching fluid from an infected person’s eyes, or from objects that carry the fluid.”
3. Brain fog
A condition described as ‘brain fog’ is usually a symptom associated with long Covid. However, some people have described experiencing it before being diagnosed with the virus.
Thea Jourdan told The Daily Mail that she first thought she may have been infected when she got a tickle in her throat and a headache.
The mum-of-three said: “Initially I felt exhausted, as if I was dragging myself through treacle and had no choice but to go to my bed. I had no meaningful cough and I wasn’t running a fever.
“I also had brain fog. I was unable even to fill out forms from the children’s schools. I just wanted to sleep, while trying to keep the kids safe and away from my quarantine area — my bedroom.”
Others have also reported struggling to hold on to thoughts or remember things throughout the day.
Christy, a woman from Seattle who withheld her surname, told the Huffington Post, how her fever progressed into “sinus congestion, a headache and a debilitating ‘brain fog’ that made it impossible to focus.
Dr Hilary Jones said those who do experience the side-effect will be faced with a “crippling” inability to think clearly.
A World Health Organisation study looking at common signs of the virus found that the third most common symptom of coronavirus was a feeling of fatigue.
Some 38.1% of patients reported the symptom in the study, which was based on 55,924 laboratory confirmed cases.
Researchers previously described fatigue as one of the ‘dark horses of Covid symptoms’, alongside headaches.
They said: “Our data shows that the most commonly experienced early symptoms are actually headache (82%) and fatigue (72%) – and this is the case for all age groups.
“Only 9% of Covid-positive adults aged 18 – 65 didn’t experience headache or fatigue.”
Despite these high levels, only 1% of people reporting fatigue and/or a headache on the app ended up testing positive for Covid.
The researchers added: “While headache and fatigue are commonly found in people who have Covid (alongside other symptoms), having either or both of those symptoms alone is unlikely to be indicative of Covid.”