Are weight loss drugs worth the side effects?

Anna-Louise Dearden | Last update: 21st June 2025

After taking Wegovy for almost a year, Sarah Le Brocq 43, was thrilled with her weight loss – but a few weeks later presented with acute vomiting and abdominal and chest pain.

“I have been overweight my whole adult life, and saw the weight management medications as a tool to support my health longer term. All was going well, but then I was admitted to hospital and it was identified that I had gallstones and an inflamed gall bladder. Working in the obesity field, I know gallstones and gallbladder issues are fairly common in people that have rapid weight loss, although it’s seen more frequently after bariatric surgery. I think it was the weight loss that triggered the attack rather than the medication, and I’ve since had my gall bladder removed.”

Despite having a procedure that would put some people off, Sarah who lives in Harrogate, says she still takes the drugs, and thinks other people should too. As long as they’re informed of the side effects.

“I think people should be aware that gall bladder issues and other side effects may occur, and to know how to identify the symptoms. But I don’t think it should deter people from taking the medications. I’m currently on

Mounjaro and have lost six stone in around 18 months. I feel great now. Better than ever!”

As frequently reported, GLP-1 weight loss drug side effects are common when taking Wegovy (semaglutide) and Mounjaro (tirzepatide), and they can affect whether people stick with the treatment. Around 80% of users in trials experienced at least one side effect – mostly gastrointestinal issues like nausea, diarrhoea, constipation or vomiting. Gallbladder problems, like gallstones, or needing removal, are rare, but serious. And semaglutide users see a two-fold risk.

Slow and steady wins the race

Speaking to SlimrChat, Jen Vittanuova, a Clinical Nurse Director and weight loss drug prescriber, agrees that if weight comes off too fast, it can sometimes increase the risk of gallstones.

“I always encourage patients to go slow and steady, stay very well hydrated (extra points if it’s clear protein water) and make sure they’re still getting some healthy fats in their diet to help keep their bodies working as well as they can.”

Bunged up

She agrees gallstones are a serious problem. But the biggest issue Vittanouva sees is far more common: constipation.

“The main side effect I see from GLP-1 medications like tirzepatide (Mounjaro) is constipation. It’s definitely the most common in my clinic, but it’s usually mild and very manageable, with a few tips. I recommend a high quality probiotic alongside a fibre supplement, and that combination has made a big difference. It helps keep everything moving and makes everything more comfortable and sustainable long term.”

Is it all weight loss drug side effects hype?

Vittanuova agrees there’s a lot of information out there that might not always be helpful. “There’s so much noise online about extreme side effects, but in reality, most people tolerate these medications really well when they’re prescribed properly and supported and monitored throughout. They’re not a quick fix; you still need to eat properly, stay hydrated, exercise and have someone medical monitoring you but they can be a useful tool in a structured plan.”

Le Brocq, who lost that six stones and feels better than ever, agrees that the medication should be supported by the appropriate wrap-around care. 

“I am a scientist by background, so I knew the evidence and data around the medications and knew they had safety data. People should only take these prescription medications if they live with obesity…i.e. their BMI is higher than 30, and, with nutritional, psychological and physical health support. They should not just be taken on their own without thought for the full health picture.”

Practical tips from a practitioner:

Jen Vittanova – feeling nauseous, dizzy or generally unwell?

• Eat small, not too spicy meals
• Stay hydrated
• Avoid fatty or rich foods
• Time your dose to suit your routine
• Try ginger tea or anti-nausea remedies (with GP approval)
• Ask about dose adjustments
• Log symptoms and track patterns

When to Seek Help

• Severe or persistent nausea and vomiting
• Severe stomach pain
• Pain under the right ribs, fever, yellowing of the skin/eyes (jaundice)
• Rash, itching, swelling (especially of face/tongue/throat), difficulty breathing
• Sudden vision changes

Your SlimrChat takeaway

Slow and steady wins the race.

As we’ve seen across the SlimrChat forums and features, these jabs are powerful, but they’re not magic. You still need to eat like yourself, pace the journey, and tune in when your body is waving red flags. There’s no gold medal for pushing through feeling grim. 

Having a good GP, a few mates on the same path, and a fridge full of healthy (but tasty) food helps too.

10 easy tips to avoid side effects.

Join us on the SlimrChat Forums to share your experience, swap tips, and stay on track.

As always, you’ve got this, and we’ve got you.