The NHS has urged Brits taking a commonly prescribed medication to seek immediate medical help if they experience any of three symptoms. These are some of the serious complications of dapagliflozin.

Also known under its brand name Forxiga, dapagliflozin is mainly used to treat type 2 diabetes. However, it is also given to patients with heart failure and chronic kidney disease.

While figures on exactly how much dapagliflozin is prescribed in the UK every year are not available, it is one of the most costly medications, with the NHS spending around £300m a year on it in England.

Dapagliflozin can also come combined with other diabetes medicines. Brand names include Xigduo (dapagliflozin with metformin) and Qtern (dapagliflozin with saxagliptin).

However, on its website, the NHS warned that "like all medicines", dapagliflozin can cause some unwanted side effects. The health body said you should "Call your doctor or call 111 now" if:

• You have a very dry or sticky mouth, feel very thirsty, sleepy or tired, are not peeing (or peeing very little), and have a fast heartbeat - these can be signs of dehydration
• You have a high temperature (or feel hot, cold or shivery), get a burning feeling when peeing, have pain in your back or side, or blood in your urine - these can be signs of a urinary tract infection (UTI)
• You get severe pain, tenderness, redness, or swelling in the groin or perineal area accompanied by a high temperature or feeling unwell - this may be a sign of a serious infection called Fournier's gangrene

However, these side effects are "rare" and occur in less than one in 10,000 people. There are some more common side effects, which happen in more than one in 100 people.

The NHS said: "They're usually mild and do not last long. There are things you can do to help cope with them."

These side effects are:

• Thrush
• Back pain
• Peeing more than normal
• Feeling dizzy
• Mild skin rash

The NHS said: "Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away."

Taking dapagliflozin with other diabetes medicines, including insulin or sulfonylureas like gliclazide, can also cause your blood sugar can sometimes go too low.

Find out about the symptoms you need to watch out for and get health advice with our free health newsletter from the Daily Express

Some people taking dapagliflozin may also experience diabetic ketoacidosis (DKA). This happens when your body starts to run low on insulin and harmful substances, called ketones, build up in the body.

Signs of DKA can include:

• Feeling or being sick
• Feeling very thirsty
• Feeling confused or unusually tired
• Having stomach pain
• Breath that smells fruity (like pear drop sweets, or nail varnish)
• Breathing more deeply or faster

The NHS says: "Symptoms usually develop over 24 hours, but can come on faster. Your doctor will show you how to monitor your ketone and blood sugar levels, and what to do if this happens.

"You'll learn how to recognise the symptoms of DKA and what to do about it." You should call 999 if you have a serious allergic reaction (anaphylaxis) to dapagliflozin.