Common GLP-1 Side Effects Every Patient Should Know

The arrival of the UK's first GLP-1 weight loss tablet has sparked fresh interest in medications designed to help people lose weight, but doctors say understanding the possible side effects is just as important as understanding the benefits.

With more people across Newcastle and the North East exploring prescription treatments such as Wegovy tablets, Wegovy injections and Mounjaro, healthcare professionals are reminding patients that these medicines should always be taken under medical supervision.

Although many people tolerate GLP-1 medications well, they can cause side effects, particularly during the first few weeks of treatment while the body adjusts.

The most common side effects.

The vast majority of reported side effects affect the digestive system.

According to the Medicines and Healthcare products Regulatory Agency, nausea, vomiting, diarrhoea and constipation are the most common reactions and may affect more than one in ten people taking GLP-1 medicines. These symptoms are usually temporary and often improve as treatment continues.

A recent medical review also found gastrointestinal symptoms remain the most frequently reported problems across both GLP-1 injections and newer oral medications, making them the main reason some patients decide to stop treatment.

Doctors often recommend eating smaller meals, avoiding high-fat foods and drinking plenty of water to help reduce discomfort during the early stages of treatment.

Pill or injection - are the side effects different.

Whether someone takes a weekly injection or a daily tablet, the side effect profile is broadly similar because both medicines work by activating the same GLP-1 receptors in the body.

The tablet does have one important difference. Patients must take it after fasting for at least eight hours with only a sip of water, then wait at least 30 minutes before eating or drinking. Failing to follow these instructions can reduce how much medicine the body absorbs.

Healthcare professionals say the gradual increase in dosage is designed specifically to reduce stomach-related side effects.

Rare but more serious risks.

While serious complications remain uncommon, patients should know the warning signs.

The MHRA has previously reminded healthcare professionals that severe dehydration can develop if persistent vomiting or diarrhoea is left untreated. Low blood sugar can also occur in some non-diabetic patients using GLP-1 medicines for weight management.

Earlier this year, the regulator also highlighted a small risk of acute pancreatitis, an inflammation of the pancreas that requires urgent medical attention. Symptoms can include severe abdominal pain that spreads to the back, alongside nausea and vomiting.

Patients experiencing severe or persistent symptoms are advised to contact their GP or seek urgent medical advice rather than continuing treatment without guidance.

Why more people are considering GLP-1 treatments.

Interest in weight loss medication has risen sharply across the UK.

Recent research suggests around 1.6 million people in England, Wales and Scotland used GLP-1 medicines between early 2024 and early 2025, reflecting the rapid growth in demand for prescription weight management treatments.

Meanwhile, official figures show around 26.5 percent of adults in England are living with obesity, while approximately two in three adults are overweight or obese, highlighting why demand for new treatment options continues to increase.

For many people in Newcastle and across the North East, obesity is linked to an increased risk of type 2 diabetes, heart disease and high blood pressure, making effective weight management an important public health priority.

What Newcastle patients should know.

Healthcare professionals across Newcastle continue to advise that GLP-1 medicines are not quick fixes.

The best results are seen when medication is combined with healthier eating habits, regular physical activity and ongoing medical support. Buying medicines from unregulated online sellers also carries significant risks, with the MHRA warning about counterfeit products entering the market.

As more people in the North East begin considering the newly available GLP-1 tablet alongside existing injections, understanding both the benefits and potential side effects will help patients make informed decisions with their healthcare provider.

Share your experiences.

Have you had any of these side effects when using GLP-1 Medicines?