Weight loss jab users face an added hurdle when it comes to protecting themselves against the flu, a leading pharmacist has warned. 

The number of hospital beds in England occupied by infected patients is already higher than ever for this time of year, with 'no peak in sight.' 

Health officials have warned the virus has plunged an already-strained NHS into a 'worst case scenario situation,' with projections suggesting there could between 5,000 and 8,000 hospital cases by the end of the week. 

For context, prior to the current outbreak, the highest ever recorded was 5,400. 

The latest data shows that searches for cold and flu tablets are also up by some 4,400 per cent across the UK this month, whilst rates of the winter vomiting bug norovirus are up 35 per cent in hospitals compared to last week, as winter viruses take hold. 

Officials have repeatedly urged for more people to get vaccinated against the flu, arguing it is the most effective weapon for reducing the risk of serious illness. 

But the jab takes up to 14 days to fully come into effect, meaning that people who are yet to have the jab won't be protected until after Christmas. 

And according to Jason Murphy, Head of Pharmacy and weight loss expert at Chemist4U, this could be bad news for the estimated 1.5million people on weight loss jabs who are looking to keep the pounds off over Christmas. 

'With thousands already estimated to have the flu and more people than ever on weight loss injections in the UK, many may be facing flu season while on their medication for the first time,' he said. 

'While some common side effect of weight loss injections, like headache, fatigue and nausea resemble flu symptoms, these are usually temporary and subside within a few days to a few weeks.' 

Symptoms of the flu, however, typically develop one to three days after someone becomes infected—and whilst most cases are over within a week, people can still feel exhausted and suffer from a lingering cough for weeks afterwards. 

And even though it's a new variant, the H3N2 flu strain presents much the same: fever, cough, sore throat, muscle aches, fatigue and sometimes stomach upset. 

Murphy cautioned that for those on the jabs, a red-flag warning sign to be aware of is a change in appetite—which is a common side effect of the weight-busting medication. 

He said: 'If you start to feel unwell and your illness makes it difficult to eat three meals per day, or it's generally impacting your appetite, it's recommended to skip a dose until fully recovered.'

This should help minimise the risk of dehydration and malnutrition—both serious side-effects associated with the so-called miracle jabs.

He added: 'If you're unable to eat or drink normally, taking a medication like Mounjaro or WeGovy that reduces appetite could make flu recovery more difficult.

'Without adequate food and liquids, you won't be getting the vitamins and nutrients your body needs to fight infection.' 

The pharmacist advises users to be conscious of how much water they are drinking and learn the tell-tale signs of dehydration: darker yellow urine, dry mouth, headache, change in bowel movements and extreme fatigue. 

He added: 'It's beneficial to consider adding an electrolyte drink or rehydration solution to help boost fluid intake and maintain hydration, particularly during cold and flu season.

'Remember, staying hydrated is crucial on medications like Wegivy and Mounajro, especially while ill,' he said. 

The jabs have already been linked to a number of serious side effects including persistent vomiting and diarrhoea, which leave patients with severe dehydration. 

Dehydration is a potentially deadly condition where the body loses more fluid than a person takes in from drinking.

It typically causes headaches and dizziness but if not treated quickly can even lead to seizures, kidney failure or prove fatal.

Safety information distributed with the jabs also warns of the risk of dehydration while using the medications. 

He also advises users, like the general population, to get as much sleep as possible, keep warm and take over-the-counter painkillers to help relieve aches and pains and reduce a fever. 

He said: 'By paying attention to flu symptoms, following these steps can help you get better quicker and back to your usual dosing. 

'However, if you have concerns about managing your medication during illness, consult with your doctor for personalised guidance.' 

Other red flag warning signs to look out for include difficulty breathing, chest pain, confusion, persistent high fever, severe dehydration or symptoms that suddenly get worse.  

Older people tend to be more vulnerable to flu, partly because their immune systems are weaker, and also because they often have existing conditions which can make it easier for illnesses to take hold. 

And whilst children aged five to 14-years old seem to be driving the surge in cases, those over 85-years-old are five times more likely to be hospitalised, sparking concerns that the super spreader age group will infect elderly relatives between now and the new year. 

The overarching worry is that if the number of patients needing overnight treatment continues to rise, surpassing 5,000 patients, as Sir Jim Mackey—the Chief Executive of NHS England has predicted—then it could place 'further strain on an already buckling system.'

The warning comes as a trial giving thousands of overweight Britons Mounjaro in a bid to get them back to work has commenced. 

The first-of-its-kind trial will assess how effective the drug is on long-term health related issues like unemployment and how many sick days people take.