Are GLP1 drugs (Semaglutide) safe?

Are GLP1 drugs (Semaglutide) safe?
Photo by Kenny Eliason / Unsplash

Drugs like Ozempic, Mounjaro, Wegovy and others are helping people beat type 2 Diabetes and lose weight, but are these drugs safe?

Don't know what "GLP1" means? Check out our explainer article on "GLP1 Agonists" for an easy to understand explanation.

What does "safe" mean?

Before we can talk about whether a treatment or drug is safe, we have to discuss side-effects.

Medicine is an imperfect science and we must track, discuss and try to mitigate side effects of medicines and treatments, and figure out which side effects we do and do not want.

What side-effects do Semaglutide-based drugs (Ozempic, Wegovy, Rybelsus) have?
Ozempic vs Wegovy (source:

Many drugs have long lists of side effects, and Semaglutide based drugs are no different.

Here are the most common side effects:

  • Low blood sugar (common for people with type 2 Diabetes)
  • Upset Stomach and related symptoms (gas, heartburn, bloating)
  • Nausea
  • Vomiting
  • Stomach pain
  • Headache
  • Dizziness
  • Tiredness
  • Upset Stomach

Along with common side effects these are the most dangerous side effects (if you feel any of these you should consider contacting a medical professional immediately):

  • Changes in vision
  • Mood changes and self-harming thoughts
  • Irregular/stronger than normal heart beat
  • Faster heart rate
  • Feeling light-headed (as if you're about to pass out)
  • Swelling or lumps in the neck (signs of a thyroid tumor)
  • Severe pain in your upper stomach spreading to your back – these are a possible sign of pancreatitis
  • Fever, gray colored stools, jaundice (yellowing skin/eyes) – these are a possible sign of gallbladder problems
  • Swelling urinating less
  • Stomach cramps, vomiting, diarrhea

While some of the side effects are very dangerous, the severity can differ from person to person, and at present many of them are slow onset/possible to detect.

How often do things go wrong with people taking Semaglutide?

Luckily, not often. Serious life-threatening events or hospitalizations do not seem to occur very frequently for people taking Semaglutide.

But don't take our word for it, here's the research:

Two-year Research Study Investigating How Well Semaglutide Works in People Suffering From Overweight or Obesity - Study Results -
Two-year Research Study Investigating How Well Semaglutide Works in People Suffering From Overweight or Obesity - Study Results.

Serious Adverse Events (SAEs) in the study are defined as:

A SAE was defined as any untoward medical occurrence that at any dose results in death, or is life-threatening, or requires inpatient hospitalization or causes prolongation of existing hospitalization results in persistent or significant disability/incapacity, or may have caused a congenital anomaly/birth defect, or requires intervention to prevent permanent impairment or damage. The SAEs occurred from week 0 to week 111 is presented. The outcome measure was evaluated based on the data from on-treatment observation period, which was defined as the interval from first to last trial product administration plus 7 weeks of follow-up and excluding any period of temporary treatment interruption defined as >7 consecutive missed doses (corresponding to >7 weeks off-treatment).

In the study, 18 out of 152 people that received Semaglutide encountered serious adverse effects, compared to 20 on the Placebo.

This means that (in this study), there wasn't a meaningful increase in serious adverse events, which is a great data point in support of Semaglutide being less likely to be harmful to you.

When things do go wrong, what goes wrong most often for people taking Semaglutide?

The most common adverse effect is Gastrointestinal (i.e. your throat, gut, digestivet ract), and most of the most notable adverse effects were resolved by stopping the regimen of Semaglutide.

An example case from the study linked above was explained at

1. A 52-year-old woman with a 10-year history of diabetes presented with a 7-month history of postprandial epigastric pain with concomitant fullness, bloating, and nausea that was unrelieved after proton pump inhibitors and antispasmodics. She was initiated on weekly semaglutide subcutaneous injection 1 month prior to symptom onset, and her diabetes is currently well-managed (A1c, 5.7%). A 4-hour scintigraphic gastric emptying (SGE) test indicated delayed gastric emptying. Semaglutide was held for 6 weeks, leading to symptom resolution.6

Most reports of negative effects seem to be related to gastro intestinal problems, in older patients, and they generally resolve by stopping the treatment.

As always, it's important to talk to medical professionals when undergoing a regimen of Semaglutide-based drugs.

What about the side effects of obesity?

While it's important to know the side effects of obesity, don't forget that there are long term risks to obesity itself. Like many situations in medicine, it's a sort of "trade off" between which symptoms and side-effects are acceptable.

The CDC has great resources on obesity and phrases the risks well:

people who have overweight or obesity, compared to those with healthy weight, are at increased risk for many serious diseases and health conditions.

Obesity can highly increase risk factors for other diseases like:

  • Hypertension
  • Coronary heart disease
  • Stroke

These are huge risks, and must be weighed against the gastrointestinal problems that might be posed by Semaglutide. Avoiding short-term nausea only to leave yourself open to heart disease is probably not a great trade-off.

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