Are weight loss drugs safe? Health experts issue warning over dangerous side effects of weight loss injections

• Weight loss medications like Ozempic, Mounjaro and Wegovy are rising in popularity.
• Leading health professionals warn that these medications come with significant side effects.

Ozempic, Mounjaro and Wegovy have became household names when it comes to tackling weight loss.

The medications, which were originally a treatment for type 2 diabetes, have been changing the lives of countless people struggling with obesity.

However, leading health professionals have been warning that these medications come with significant side effects that extend far beyond suppressing your appetite.

As Sandra Roycroft-Davis, a leading behavioural change specialist and author of The Weight’s Over explains: “Ultimately, weight loss jabs don’t teach people how to sustain results once they stop taking them. Without a focus on habit formation, mindset shifts, and behavioural change, many people will find themselves back at square one.”

Drugs like Ozempic, which is a treatment for type 2 diabetes, have become household names for weight loss. | BELGA MAG/AFP via Getty Images

What are the side effects from weight loss injections?

Here are some of the side effects from weight loss drugs that could be dangerous for your health:

Hair Loss

As you lose weight, you can also lose your hair, with Dr Ross Kopelman, a hair transplant surgeon at Kopelman Hair Restoration, explaining he has seen an increase in hair thinning among patients using GLP-1 receptor agonists like Ozempic.

“Hair loss is often an overlooked side effect of rapid weight loss with these medications. While not everyone experiences it, I see it frequently enough that I always advise patients to support their hair and scalp health proactively, with proper nutrition, stress management, and sometimes targeted treatments.”

Registered trichologist and Seed & Soul founder Deborah Maguire adds: “When the body experiences a calorie deficit, it reallocates nutrients to sustain essential organs, often leaving hair follicles deprived. Weight loss medications that suppress appetite mean individuals may not consume enough of the key nutrients required to support healthy hair growth.”

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Muscle Loss

Muscle loss is particularly concerning for menopausal women, who are already vulnerable due to declining oestrogen levels, according to Roycroft-Davis, who explains: “When weight drops rapidly due to extreme calorie restriction, the body doesn’t just burn fat—it also breaks down muscle tissue for energy. Studies on GLP-1 medications suggest that as much as 40% of total weight loss can come from lean muscle mass rather than fat.”

Jordan Chadwick, Managing Director at Tonic Weight Loss Surgery, adds: “This muscle loss, known as sarcopenia, may result in decreased strength, stamina, and a lower resting metabolic rate, making long-term weight maintenance even harder.’

Ozempic Face

A common side effect that impacts facial features has become known as “Ozempic face.” Caused by rapid fat loss, it can mean your face loses volume, leading to a gaunt and aged appearance.

Dr Naheed Ali, a physician and Senior Contributor at Vera Clinic, explains: “Ozempic face is not exclusive to these drugs, any significant weight loss can lead to changes in facial structure. But for some, the effect is more dramatic than expected.”

Gastrointestinal Problems

Weight loss drugs can cause side effects including nausea, vomiting, diarrhoea, haemorrhoids and constipation, which can affect appetite, food intake, and nutrient absorption and therefore your overall health.

Dom Blonska, a personal trainer and nutrition coach, has seen extreme cases, including one of their clients ending up in hospital “with gut paralysis after taking weight loss injections.’

Other Side Effects

That’s not all, users of weight loss medications have also reported extreme fatigue and weakness, hormonal imbalances leading to missed menstrual cycles, mood swings and have a negative impact on mental health.

A recent study showed users reported low blood pressure, including fainting, headaches, disturbed sleep, kidney stones, inflammation in the kidneys and a range of bone or joint pains and potentially deadly inflammation in the pancreas.

Experts stress that potential users should address any underlying health issues before trying the jabs. Blonska warns: “There is no quick fix. If your hormones are out of balance, weight loss drugs may make things worse.”

The Physiological Impact

There is also the physiological impact of when you stop the injections, with some finding the weight can often return.

Despite the side effects studies have also suggested that weight loss drugs can significantly improve health, with one linking them to better heart health, fewer infections and fewer cases of dementia.

But one thing the experts do agree on is that you can’t go wrong with a bit of exercise and a healthy diet.

Roycroft-Davis explains: “The real conversation should be: What happens after the jab? And how do we ensure people have the right tools to maintain lasting health, strength and confidence in their own body?”

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