Weight loss drug Wegovy: The pros and cons, explained

12:50 pm on 6 July 2025

This story has been corrected as an earlier version said Wegovy AND Ozempic had been made available on prescription for weight loss in New Zealand but it is only Wegovy.

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Novo Nordisk produces the drug Wegovy. Diabetes medicine and anti-obesity injections. Active ingredient: Semaglutide. Manufacturer: Novo Nordisk.
Photo: Lise Aaserud / NTB (Photo by LISE ASERUD / NTB via AFP)

Wegovy is injected daily and promotes a feeling of fullness while silencing "food noise." Photo: LISE ASERUD

Earlier this week semaglutide drug Wegovy was made available for prescription in New Zealand.

Semaglutide originally arrived on the market in the US in 2017 as a diabetes medication, but has quickly been tied to extreme weight loss.

Wegovy can be prescribed to people over the age of 12, but many of the 65 percent of New Zealanders who are overweight or obese will have trouble affording it, with an estimated price of $500 a month.

The drug has transformed our ability to manage obesity and type 2 diabetes, and has shown potential for a wide range of conditions such as Alzheimer's, addiction and depression.

But there are clouds to go along with the silver linings - such as potential vision loss.

"This condition, it occurs when there's insufficient blood flow to the nerves connecting the eye to the brain, and this leads to damage," US-based health reporter for New Scientist, Grace Wade, told RNZ's Sunday Morning. The specific condition was non-arteritic anterior ischemic optic neuropathy.

"That can cause this sudden and permanent vision loss, usually in just one eye. Now, I should be clear this isn't total vision loss, at least usually - it's more like cloudiness, stuff like that."

People using semaglutides to treat diabetes were 4.3 times more likely to develop this condition, and those using it for weight loss 7.6 times, as people using other types of diabetes medications, a 2024 study found (Wade wrote about it in New Scientist here).

Novo Nordisk, the maker of Wegovy, said in a statement, patient safety was the top priority and all reports of adverse events were taken seriously.

"Semaglutide has been studied in robust clinical development programs with more than 52,000 semaglutide exposed patients and exposure from post-marketing use of over 33 million patient years."

It said it was recommended to update patient leaflets for Wegovy and Ozempic on June 6 to include the condition under its special warnings and precautions for use and as an adverse drug reaction with a frequency of "very rare, meaning it may effect up to 1 in 10,000 people taking semaglutide".

It said based on the totality of evidence it concluded the data did not suggest a reasonable possibility of a casual relationship between the condition and semaglutide and "the benefit-risk profile of semaglutide remains favourable".

"We work closely with authorities and regulatory bodies worldwide to continuously monitor the safety profile of our products."

The drug worked by suppressing appetite, which typically leads to weight loss as people consume fewer calories. But the weight lost was not always beneficial, Wade said.

"It leads the body to break down fat, muscle and actually even bone for nutrients, and that's why… some research has found that upwards of 40 percent of the weight loss seen with these medications is due to loss of muscle mass… that makes it really important that people prioritise exercise when taking these drugs because if you don't use your muscle, you're more likely to lose it."

Getting into the exercise habit was also important since one day, most people on Wegovy will stop taking it - putting themselves at risk of putting the weight back on if they were not regularly moving.

Then there is 'Ozempic face'.

"I don't think this is a clinical term yet, but it's something that's popped up a lot in social media," Wade said.

"People who are taking these medications start developing... a sunken or hollowed out appearance, which can exacerbate fine lines and wrinkles, make their skin look a little more saggy.

"It isn't clear exactly how common this is… but it probably has to do with just weight loss, right? If you're losing weight, as much as some people would want to target their weight loss to certain areas of their body, we can't really do that. So, you know, any sort of overall weight loss is also gonna cause a loss of fat in your face."

There were also side effects for some, including constantly needing to go to the toilet, feeling bloated, belching, constipation, heartburn, fever, upset stomach - the list, collected here by the Mayo Clinic, goes on.

And nearly half of people who try it make it through a three-month course, one study found.

Wade also mentioned a lot of people taking semaglutide for diabetes or Alzheimer's prevention might be older and "frail", so not able to lose weight.

"Drug developers are actually working to develop new drugs that have similar effects as these weight loss medications, but without the weight loss."

The good news

One unexpected benefit of semaglutide was its apparent effect on not just calorie consumption, but use of addictive substances, such as alcohol and nicotine.

"We aren't exactly sure why that is, but it appears to be with how these medications affect brain activity.

"So these drugs curb cravings for alcohol similar to how they curb cravings for food, right? And that probably has to do with their impact on brain regions involved in reward processing and craving…

"A study of more than half-a-million people with a history of opioid use disorders showed that those who took Ozempic or similar [medications] had significantly lower rates of opioid overdose than those who didn't.

Grace Wade

Grace Wade. Photo: New Scientist

"Other studies have shown similar effects in people with cannabis use disorder, cigarette smokers and alcoholism."

Scientists did not expect this effect, calling it an "unintended consequence".

The drugs have also shown promise in reducing heart attacks and strokes, improving fertility, treating pain, improving mental health, lower the risk of kidney failure and slowing cognitive decline.

"I've never encountered a group of drugs like this," Wade said. "That's what makes these drugs so remarkable, because most medications can only treat one or two conditions, right?"

She said it was likely that weight loss was playing a role - as it frequently does in health - but "it doesn't seem to be the only [reason]".

But there is still a lot of research to be done, she said, before we all start taking it.

"Let's unravel how they can treat all of these conditions before we jump the gun and start suggesting we, you know, maybe put it in everyone's water or something."

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