Ozempic Side Effects: What’s Normal and When to Worry

The most common Ozempic side effects are nausea, diarrhoea, vomiting and constipation. For most people they are mild, show up in the first weeks and after each dose increase, and fade with time. A few rare ones, such as pancreatitis, need a doctor straight away. Here is what to expect if you are thinking about Ozempic for weight loss.^1,2

How common are Ozempic side effects?

Very common, but mostly mild. Ozempic and Wegovy contain the same medicine, semaglutide. In the weight-loss trials of semaglutide at 2.4 mg a week, these were the most frequent side effects, compared with a dummy injection:¹

• Nausea: 44% of people, against 16% on placebo.
• Diarrhoea: 30%, against 16%.
• Vomiting: 24%, against 6%.
• Constipation: 24%, against 11%.
• Stomach pain: 20%, against 10%.
• Headache and tiredness: 14% and 11%, against 10% and 5%.

The key number is this one: about 7 in 100 people stopped because of side effects, against 3 in 100 on placebo.¹ In the main trial, nausea and diarrhoea were usually mild to moderate and settled with time.³

What’s normal in the first weeks?

The first month uses a low starting dose of 0.25 mg, so your stomach can get used to the medicine. The dose then rises step by step, no faster than every four weeks.^1,2 Stomach side effects tend to come back for a few days after each step, then ease.

Feeling full quickly, eating much less and going off fried or heavy food are expected. That is the medicine working: it slows how fast your stomach empties and calms appetite. Many people feel a little queasy for a day or two after each weekly injection.

How can I ease nausea and stomach upset?

• Eat smaller meals, slowly, and stop as soon as you feel full.
• Go easy on oily, fried and very sweet food, especially at dinner.
• Sip water through the day. Vomiting or diarrhoea can dry you out, and dehydration can strain the kidneys.¹
• Don’t lie down straight after eating.
• If constipation starts, add fibre and fluids slowly, and ask about a gentle laxative.
• Tell your doctor if side effects are hard to live with. Staying on a dose longer before the next step often helps. If they still don’t settle, your doctor may suggest a different medicine, such as Mounjaro. See how the two compare in Mounjaro vs Ozempic.

Ozempic side effects in women

Most side effects are the same in women and men. Two points matter more for women:

• Pregnancy: semaglutide isn’t used in pregnancy or while breastfeeding. Stop it at least 2 months before you try for a baby, because it stays in the body for weeks.¹
• Hair shedding: 3% reported hair loss on semaglutide, against 1% on placebo.¹ Fast weight loss itself can trigger shedding a few months later. It usually settles, and our hair fall treatment page covers what helps if it doesn’t.

What is “Ozempic face”?

It’s a nickname, not a medical side effect. When you lose a lot of weight, you lose fat from your face too, so cheeks can look hollow and skin can look looser. It happens with any big weight loss. Losing weight gradually helps. If it bothers you later, a skin booster such as Profhilo or fillers can restore some softness, once your weight has settled.

Rare but serious side effects

These are uncommon, but you should know the warning signs:^1,2

• Pancreatitis: severe stomach pain that doesn’t go away, sometimes spreading to the back, with or without vomiting. Stop the injection and get medical help at once.
• Gallstones: 1.6% had gallstones on semaglutide, against 0.7% on placebo.¹ Watch for pain under the right ribs, fever or yellow eyes.
• Low blood sugar: mainly if you also take insulin or certain diabetes tablets. Your doctor may lower those doses.
• Sudden loss of vision: Europe’s medicines regulator lists an eye condition called NAION as a very rare side effect, in up to 1 in 10,000 people.⁴ Sudden vision loss needs urgent care. People with diabetic eye disease also need eye checks.
• Before surgery: tell your surgeon and anaesthetist you take it, because a slow-emptying stomach can be a risk under anaesthesia.¹

Does Ozempic cause cancer?

There’s no proof it does in people. Semaglutide caused thyroid tumours in rats and mice, and it isn’t known whether that applies to humans.^1,2 As a precaution, it isn’t prescribed if you or a close relative has had medullary thyroid cancer or MEN 2 syndrome. Tell your doctor about any lump in your neck, trouble swallowing or a hoarse voice that doesn’t go away.

What happens when you stop?

The side effects fade within weeks, but the weight tends to come back. In a follow-up of the main trial, people regained about two-thirds of the weight they had lost within a year of stopping.⁵ That is why we plan eating and activity habits alongside the injection from day one.

Are fake pens a risk?

Yes. DRAP, Pakistan’s medicines regulator, has warned about falsified weight-loss injections, including ones sold online.⁶ A fake pen can contain the wrong dose or no medicine at all. Buy only on a prescription, from a licensed pharmacy or clinic, never from social media.

When should I call a doctor?

• Vomiting or diarrhoea for more than a day, or you can’t keep fluids down.
• Severe or lasting stomach pain.
• Signs of dehydration: very little urine, dizziness or a dry mouth.
• Sudden changes in your eyesight.
• Shakiness, sweating or confusion if you also take diabetes medicine.

Questions people ask

How long do Ozempic side effects last?

For most people, stomach side effects last a few days after starting and after each dose increase, then settle within weeks. If they don’t, your doctor can slow down the dose increases.

Is Ozempic safe for weight loss?

Semaglutide has been studied in thousands of adults, and most side effects are mild. It’s safest when a doctor checks that it suits you, raises the dose slowly and follows you up. It isn’t meant for losing a few kilos before an event.

Are the side effects worse at higher doses?

They are more likely during dose increases. That is why the dose goes up in small steps, at least four weeks apart.

Can I take Ozempic if I have PCOS or thyroid problems?

Your doctor decides after going through your history. PCOS and common thyroid problems aren’t listed reasons to avoid it, but a personal or family history of medullary thyroid cancer is.¹

Talk to a doctor first

Weight-loss consultations are free at all 12 of our clinics. A doctor checks your BMI, health and medicines before prescribing anything, and follows you up at each dose step. Compare the weight loss injection price in Pakistan across our options, or see Ozempic in Lahore. Have a question first? Message us on WhatsApp and we reply.

Medically reviewed by Dr Sadaf Saleem, Dermatologist, FCPS (Dermatology), PM&DC 62494-P; Dr Junaid Rabbani, Dermatologist, PM&DC 44510-S; and Dr Shegref Mushtaq, Dermatologist, FCPS (Dermatology), PM&DC 19827-N

1. US National Library of Medicine. WEGOVY (semaglutide) injection: prescribing information. DailyMed.
2. NHS. Semaglutide.
3. Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med, 2021.
4. European Medicines Agency. PRAC concludes eye condition NAION is a very rare side effect of semaglutide medicines. 2025.
5. Wilding JPH, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes Obes Metab, 2022.
6. Drug Regulatory Authority of Pakistan. Rapid Alert I/S/07-23-24: suspected falsified GLP-1 receptor agonists. 2023.

Treatments in this article

Sessions, downtime and results for each, on its own page.

Ozempic & Wegovy InjectionsAppointment: Under a minute, at home · Downtime: None; tummy upset early onMounjaro Injection for Weight LossAppointment: A few seconds per injection · Downtime: None; nausea is common at firstSemaglutide InjectionAppointment: About 30 minutes a visit · Downtime: None; tummy upset early on

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