Every Ozempic Side Effect, Explained

This content originally appeared here. Republished with permission.

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By Ross Wollen

Medically Reviewed by Sean Hashmi, MD

Ozempic and other drugs in the GLP-1 receptor agonist family have rapidly become famous for dramatic weight loss, but every few weeks it also seems we hear that social media users are shining a light on another new Ozempic side effect. These reactions include hair loss, fierce gastrointestinal distress, rare (but severe) stomach paralysis, and some unique Ozempic side effects in females. Some of these secondary effects have been scientifically verified, while others are still just anecdotal.

GLP-1 medications can cause any or all of these symptoms.
Everyday Health

A brief note: This article uses the brand name Ozempic to refer to semaglutide, the drug’s active ingredient. Semaglutide is also marketed under two other names, Wegovy (when sold for weight loss) and Rybelsus (in the form of a pill rather than an injection). Other related drugs, such as liraglutide (Victoza) and tirzepatide (Mounjaro, Zepbound) may cause some of the same side effects.

Stomach Problems: Nausea, Diarrhea, Vomiting, Abdominal Pain, and Constipation

These uncomfortable gastrointestinal troubles make up Ozempic’s most common and most discussed side effects by far.

While a majority of users don’t perceive these pains, a very substantial minority do. According to the U.S. Food and Drug Administration (FDA), placebo-controlled trials of Ozempic found the following rates of side effects from the 1 milligram (mg) dose:^[1]

Gastrointestinal Side Effects of Ozempic (1mg)

All told, 30.8 percent of adults reported a gastrointestinal symptom.^[1] But that was only the 1 mg dose, half of the maximum. The numbers were much higher in a trial of semaglutide (Wegovy) at 2.4 mg in people without diabetes:

Gastrointestinal Side Effects of Wegovy (2.4mg)

At this, the highest dosage of semaglutide available, an incredible 74 percent of participants experienced at least one gastrointestinal disorder, though it’s worth noting that nearly 50 percent of those who took a placebo also had some tummy troubles.^[2]

For some, the gastrointestinal distress is just too much to handle, and they need to stop taking Ozempic entirely. As a blogger for New York magazine’s The Cut put it, “You might go through hell for your post-Ozempic body.” The author spoke to a 42-year-old woman with diabetes who endured “constant nausea” and “power-puking” for weeks, before finally weaning herself off the drug.^[3] In a pivotal trial, 4.5 percent of Wegovy patients stopped taking the medication as a direct result of gastrointestinal disorders — nearly 1 in every 20.

What’s the best way to deal with these nasty problems? Everyday Health’s network site Diabetes Daily has an entire article on the subject.

Reports from the Diabetes Daily forum suggest that these unfortunate effects are strongest in the days immediately after injecting the once-weekly medication. Patients are also most likely to experience problems when they start on the drug or when they step up to a higher dosage; the side effects commonly fade away as the body gets used to the medicine.

Ozempic Burps

A foul-smelling burp isn’t exactly the most debilitating of side effects, but it can be rather unpleasant. As reported in The Atlantic, and discussed in many YouTube and TikTok videos, some people taking Ozempic find themselves emitting nasty sulfurous smells when they belch.^[4] There is broad agreement that the burps smell like rotten eggs.

Only a minority of semaglutide trials have identified burping, or “eructation,” as a side effect. Anecdotal reports suggest that the burps, like other gastrointestinal issues, are worse when patients begin taking their drugs or step up to higher dosages.

Bloating and Farting

These uncomfortable side effects were reported in clinical trials as “abdominal distension” and “flatulence.” Bloating and farting complaints are less common than the gastrointestinal effects discussed above, and they have yet to catch on as hot topics on social media, but it’s good to know that Ozempic and related drugs may increase their likelihood.

Stomach Paralysis (Gastroparesis)

Weight loss drugs such as Ozempic have been tied to a rare but increased risk of severe stomach problems. In July 2023, CNN reported that some semaglutide users had experienced gastroparesis, or stomach paralysis, which in some cases did not get better even months after discontinuing the medicine.^[5] Dozens of lawsuits have been filed against the manufacturers of GLP-1 medications, according to Reuters, alleging that the makers did not sufficiently warn users about the risk of severe side effects such as gastroparesis.^[6]

Gastroparesis is a condition in which the stomach empties too slowly or stops; it causes a variety of gastrointestinal symptoms including bloating, abdominal pain, nausea, and vomiting.^[7]

In the worst cases, gastroparesis can make it very difficult to eat or drink anything at all, leading to a risk of dehydration or malnutrition.

Delayed stomach emptying, the defining feature of gastroparesis, is a known consequence of Ozempic and related drugs. This delayed emptying partially accounts for some of Ozempic’s positive effects, helping to reduce hunger and provoke weight loss. It is also responsible for less severe side effects, such as gastrointestinal discomfort.

Luckily, severe and persistent gastroparesis appears to be very rare. The symptom was not identified in any of the drug’s phase 3 trials, which enrolled thousands of participants to evaluate semaglutide’s safety.

Temporary Intestinal Paralysis (Ileus)

Stomach paralysis isn’t the only severe gastrointestinal side effect that users have reported.

In late September 2023, the FDA updated the official Ozempic label to warn users of a potential risk of ileus, a type of intestinal blockage.^[8] According to the Cleveland Clinic, ileus occurs when “the muscle contractions that move food through your intestines are temporarily paralyzed,” trapping food within the gut. The symptoms resemble those of a physical bowel obstruction, including bloating and constipation, and the condition can lead to dehydration.^[9]

Ileus is likely a rare side effect — it wasn’t identified in previous clinical trials, which evaluated semaglutide in thousands of participants. In its updated guidance, the FDA noted, “Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.”

Ozempic Face and Ozempic Butt

“Ozempic face” may have been the first Ozempic side effect to go viral. Soon after, the pattern repeated itself when claims of “Ozempic butt” hit headlines. In each case, users complained that the drug had given some part of their bodies a surprising and unfortunate flabby appearance.

There’s nothing to worry about. There is no evidence that Ozempic or any other similar drug directly affects your appearance. Experts seem to agree that Ozempic face and Ozempic butt are purely caused by weight loss. The same flabby results can and will occur when you lose weight the old-fashioned way, or through other medical methods such as bariatric surgery.

It turns out that not all weight loss enhances your appearance. When you lose a lot of weight, you might also lose some healthy-looking fat that you’d prefer to keep in places like your face or butt. Rapid weight loss can also lead to saggy skin: The skin is an adaptable and elastic organ, but it cannot snap instantly back into a taut shape. Successful dieters have struggled with these issues since long before Ozempic came on the scene.

Ozempic Breath and Dry Mouth

Bad breath is typically a matter of oral hygiene.^[10] Food particles and bacteria in the mouth can create foul odors. Though in some cases bad breath (halitosis) can signal a more substantial medical condition, experts seem unworried that Ozempic breath is a serious sign.

How does Ozempic cause bad breath? One possible explanation is Ozempic’s tendency to cause dry mouth (xerostomia). Saliva helps to cleanse the mouth, and a lack of saliva can allow bacteria to fester, grow, and get stinky. Though dry mouth was not initially reported among semaglutide’s known side effects, it has been widely discussed in social media and clinicians have published reports of extreme cases.^[11]

“Keto breath” may also explain some cases of Ozempic breath. This side effect is common when people switch to a keto diet, which strictly limits the number of carbohydrates you are allowed to eat. Keto breath, which tends to have a fruity aroma, is caused by acetone, a by-product of ketosis. It is probable that some Ozempic users have unintentionally adopted a ketogenic eating pattern as a result of their diminished appetites — eating 50 grams or less of carbohydrates per day can trigger ketosis.

Hair Loss

Ozempic can cause hair loss. While it isn’t listed as a side effect on Ozempic’s FDA label, hair loss is listed on the FDA’s label for Wegovy, essentially the same medication. Three percent of participants in the drug’s pivotal trial reported hair loss (3 times as many as those who used a placebo).^[2]

Like Ozempic face and Ozempic butt, however, this is merely a common consequence of rapid weight loss. Dramatic weight loss, no matter how it’s caused, often causes hair loss. This science is well-established. For example, a study of crash dieters published in 1974 found multiple cases of “profuse hair loss.”^[12] And more than half of people who receive bariatric surgery experience hair loss, too.^[13]

The good news: One study found that “hair loss stopped and new hair gradually grew out in all patients.”^[14]

Hopefully, the minority of Ozempic users who lose some hair on the drug will have the same good luck.

Ozempic Side Effects in Females

As far as research goes, most of semaglutide’s side effects are common to both males and females, and there is no special interaction between GLP-1 drugs and female hormones. But there are certain Ozempic side effects that specifically affect women.

Ozempic Babies

We may be experiencing an Ozempic baby boom. Across social media, women are crediting surprise pregnancies to their GLP-1 medication.

Though there’s no solid data on the phenomenon, experts agree that Ozempic has a number of different features that could account for increased fertility. Obesity itself has long been known to cause subfertility and infertility, so the dramatic weight loss associated with Ozempic could easily increase a woman’s chances of conceiving.^[15] The effect may be even stronger when weight loss and metabolic improvements help improve or alleviate a condition like polycystic ovary syndrome (PCOS).

There is also a chance, however, that Ozempic could interfere with the birth control pill. Today, there is no scientific evidence that this happens, but a related drug in the class, tirzepatide (Mounjaro, Zepbound), carries warnings on its FDA labels that it “may reduce the efficacy of oral hormonal contraceptives due to delayed gastric emptying.” Patients are advised to switch to a non-oral form of contraception or to add a barrier method, such as condoms.^[16]

Ozempic Breasts

First, there was Ozempic face, then, there was Ozempic butt. Finally, complaints of “Ozempic breasts” hit headlines in the spring of 2024.

Women who have lost weight with Ozempic and other GLP-1 medications are complaining that their breasts have a saggy or deflated appearance. But there is no evidence that Ozempic has a particular effect on breast tissue. Rather, any change in breast shape is almost certainly due to the rapid and substantial weight loss that these drugs so frequently cause. Women who have lost weight with other methods have noticed the same issue.

Tiredness and Fatigue

There are reports that Ozempic can cause fatigue — basically, tiredness or exhaustion that isn’t improved by sleep. The FDA label for semaglutide (Wegovy) reports that 11 percent of trial participants experienced fatigue, a little bit more than twice as often as those who used a placebo.

It’s unclear why Ozempic would cause fatigue, although one very plausible explanation is the fact that it causes people to eat so much less food. Ozempic causes extreme weight loss by encouraging users to eat at an extreme calorie deficit. You’re putting less fuel into your body, essentially crash dieting. Is it any wonder that Ozempic might sap your energy?

Dizziness

Dizziness has also been reported in a slim minority of Ozempic users. It is possible that Ozempic dizziness stems from the glucose-lowering effects of the drug — dizziness is a common symptom of hypoglycemia. Even patients who are not at risk of severe hypoglycemia (typically those who do not use insulin or sulfonylureas) may feel dizzy while experiencing transient low blood sugar episodes.

Excessive Muscle Loss

It is inevitable that weight loss will involve some muscle loss. This is considered healthy and natural.

Some experts, however, believe that Ozempic and related drugs are causing a surprising and worrying amount of muscle loss.

We only have a modicum of good data on this question. Body composition analyses of volunteers in two trials found that semaglutide users lost about 40 percent lean mass and 60 percent fat.^[17] This is more muscle loss than researchers expect to see. A review published in 2017 stated that people using other methods to lose weight tend to lose only 20 to 30 percent lean mass.^[18]

In February 2024, The New York Times reported that the manufacturers of GLP-1 drugs are taking the problem seriously, and have begun to develop combination drug treatments that could help users of Ozempic and related drugs preserve lean mass.^[19]

In the meantime, experts agree that it would be wise for users to engage in strength-building exercises to help preserve muscle mass during weight loss. Eating enough protein may also help.

This potential side effect may also be a good reminder that Ozempic is inappropriate for people who do not have a good medical reason to lose weight.

Relief From Food Noise, Desire to Drink, and Addictive Behaviors

Many Ozempic users are amazed to find that they are engaging in less addictive and compulsive behavior. Somehow the drug appears to reduce our damaging tendency to overindulge in activities like drinking, shopping, gambling, or even biting our nails.

The science here is still in its infancy, but it appears that one of the reasons Ozempic is able to stem hunger cues is by acting directly in the brain.^[20] We know that Ozempic doesn’t just help you feel full faster, it actually lowers your craving for food, switching off the food noise that compels some people to perpetually fixate on their next snack or meal. And it seems as if the drug reduces your craving for other things, too.

Experts have known for years that GLP-1 receptor agonists might have these behavioral effects. In a study of exenatide (Byetta), brain scans showed that the drug lowered activity in “crucial brain areas for drug reward and addiction.”^[21] It also calmed down the brain’s dopamine circuitry. Multiple clinical trials are now underway to explore the potential of GLP-1 drugs as anti-addiction medication.

We are years away from the day that Ozempic or any related drug could be prescribed as a therapy for addictive or compulsive behavior. But in the meantime, it could help users with more than just compulsive eating.

Suicidal Thoughts

Government health authorities in the United States, and European Union initially signaled concern that semaglutide and other GLP-1 drugs were causing thoughts of suicide and self-harm.

A thorough review of the evidence, however, appears to have set those concerns to rest. In January 2024, the FDA announced that it could not identify a “causal link” between GLP1 drugs and suicidal thoughts or actions.^[22] In April, EU regulators made a similar announcement.^[23]

Today, the official FDA labels for Wegovy and Zepbound continue to warn that there is a risk of suicidal ideation, but the agency clarified in its announcement that the warning is based on evidence from “older medicines used or tested for weight loss.”

Increased Heart Rate

There’s been relatively little online chatter about this side effect, which is noted on Ozempic’s FDA label. In clinical trials, lower doses of Ozempic “resulted in a mean increase in heart rate of 2 to 3 beats per minute.” Some patients have found the experience uncomfortable.

The FDA advises patients to “inform their healthcare providers of palpitations or feelings of a racing heartbeat while at rest.” Those who experience “sustained” increases in resting heart rate should discontinue the medication.

While this side effect seems disconcerting, it’s worth remembering that semaglutide and tirzepatide have overwhelmingly positive effects on heart health. Semaglutide was recently approved as a treatment for the prevention of heart attacks, and preliminary studies suggest that tirzepatide also imparts broad cardiovascular benefits.^[24]

Diabetic Retinopathy

People with diabetes should know that there is some evidence that Ozempic may increase the incidence of diabetic retinopathy, a form of eye disease that can lead to vision loss. According to Pharmacy Times, one of several pivotal studies of semaglutide found an increased risk of diabetic retinopathy,^[25] and the FDA has reported that a significantly higher percentage of Ozempic users have DR in comparison with users of similar drugs like dulaglutide (Trulicity) and liraglutide (Victoza).^[26] The connection is disputed, however, as another large study of semaglutide found no such risk.^[27]

If the connection is real, it seems possible that Ozempic’s incredible effectiveness explains its negative effect on the eyes. Contrary to all expectations, rapid improvement in glucose control can actually worsen diabetic retinopathy. This is called “early worsening,” because the eyes will get worse before the major long-term benefits of better blood sugar control become evident.

A recent discussion of the issue by experts from the American Academy of Ophthalmology suggested that “early worsening” from Ozempic is both temporary and manageable, although it does call for increased scrutiny from eye doctors.^[28]

There is no evidence that people without diabetes have any reason to worry about their eyesight on Ozempic.

Low Blood Sugar (Hypoglycemia)

While Ozempic probably does not itself cause hypoglycemia, its glucose-lowering effect can sharply increase the odds that other drugs, principally insulin or sulfonylureas, cause hypoglycemia. If Ozempic lowers your baseline blood sugar level, your old dosage of glucose-lowering medication may now be more than you need.

If you have diabetes and you’re starting a new GLP-1, you may need to change the dosages of the other diabetes drugs that you use. Your doctor may also ask you to be extra vigilant about checking your blood sugar. If you’re not comfortable changing your insulin-dosing practices by yourself, you should be ready to contact your doctor between visits to get guidance on making adjustments.

Erectile Dysfunction

A study published in February 2024 revealed that men without diabetes who use semaglutide could be 10 times more likely to experience erectile dysfunction, (1.4 percent total, vs only 0.14 percent in a control group). The risk of hypogonadism (low testosterone) also sharply increased.^[29] The report confirmed anecdotal evidence on social media, where some men have complained that the drug has lowered their sex drive or made it more difficult to maintain an erection.

This result surprised the study’s authors because weight loss usually improves erectile dysfunction.^[30] The science is still unclear, however, as other studies have found that GLP-1 medications can actually increase testosterone levels and improve erectile dysfunction.^[31][32]

There are many treatments for erectile dysfunction, both pharmaceutical and natural.

Rare, Serious Side Effects

Semaglutide also leads to a small number of rare but potentially serious side effects:

• Pancreatitis This condition, in which the digestive enzymes attack the pancreas, may feel like intense stomach pain that radiates to your back.
• Kidney Failure Research indicates that some cases of semaglutide contribute to kidney disease.^[33] Dehydrating side effects, particularly diarrhea and vomiting, may enhance this risk. Nevertheless, for most people the drug appears to have a positive effect on kidney health.
• Gallbladder Disease This may cause severe stomach pain, yellowing of the eyes or skin, fever, and “clay-colored stools.”
• Thyroid C-Cell Tumors Semaglutide’s FDA labels warn of the risk of developing thyroid cancer, which has been observed in studies of rodents. A European health authority, however, has announced that it couldn’t find any link in humans.^[34]

There have also been some reports of allergic reactions to GLP-1 receptor agonists.

Ozempic is powerful stuff: If you’re experiencing a reaction that you can’t explain, please reach out to your healthcare provider.

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