Updated on March 8, 2026 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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Table of contents
- Orlistat vs. Ozempic®: At a Glance
- Orlistat (Xenical® And Alli®)
- Ozempic®
- Considering GLP-1 Medications
- Related Content
Orlistat and Ozempic® promote weight loss in different ways. Older medications such as orlistat (Xenical® or Alli®) work by reducing the amount of dietary fat the body absorbs. Newer medications like Ozempic® focus instead on appetite regulation, helping people feel fuller for longer and reducing overall food intake.
Ozempic® is a once-weekly injectable medication originally approved by the FDA to treat type 2 diabetes. Its active ingredient, semaglutide, is also used in Wegovy®, a higher-dose medication approved specifically for weight management.
Below, we compare how these medications work, their potential side effects, and what to consider when evaluating weight loss treatment options.
Orlistat vs. Ozempic®: At a Glance
Orlistat and Ozempic® are both used to support weight loss, but they work in very different ways. The table below highlights some key differences between these medications.
| Feature | Orlistat (Xenical® / Alli®) | Ozempic® |
|---|---|---|
| Medication type | Fat absorption inhibitor | GLP-1 receptor agonist |
| How it works | Blocks about 30% of dietary fat from being absorbed in the intestines | Mimics the GLP-1 hormone to regulate blood sugar, slow digestion, and increase feelings of fullness |
| How it is taken | Oral pill taken with meals | Once-weekly injection |
| Primary FDA approval | Weight management | Type 2 diabetes treatment (sometimes prescribed off-label for weight loss) |
| Expected weight loss | Up to ~6% of body weight for some individuals | Up to ~15% body weight reduction in clinical trials when combined with lifestyle changes |
| Common side effects | Gas, oily stools, increased bowel movements, upset stomach | Diarrhea, constipation, injection-site reactions, gastrointestinal symptoms |
| Prescription status | Prescription (Xenical®) or over-the-counter (Alli®) | Prescription only |
Orlistat (Xenical® And Alli®)
Orlistat works by slowing the absorption of fat in the intestine by about 30%. It is approved for long-term use.
About 6 lbs (3 kg), or up to about 6% of body weight, may be lost while using this medication. However, not everyone experiences weight loss with orlistat, and many people regain weight within two years after stopping the medication.
Xenical® is the prescription version of orlistat. A lower-dose version is available over the counter under the name Alli®. These pills are about half the strength of Xenical®. Orlistat typically costs around $100 or more per month.
Because orlistat affects fat absorption, it may also reduce your body's ability to absorb certain vitamins and nutrients. For this reason, people taking orlistat are often advised to take a daily multivitamin.[1]
According to the Cleveland Clinic, orlistat should be used alongside a reduced-calorie diet that contains no more than about 30% of calories from fat. Distributing your daily intake of fat, carbohydrates, and protein evenly across meals may help improve results and reduce side effects.
What Potential Side Effects May I Notice When Taking Orlistat?
Side effects that should be reported to a healthcare provider as soon as possible include:
- Allergic reactions such as rash, itching, or swelling of the face, lips, or tongue
- Breathing problems
- Bloody or black stools
- Symptoms of kidney stones (blood in urine or lower back pain)
- Symptoms of liver injury such as yellowing of the skin or eyes
- Trouble passing urine
- Uncontrolled or urgent bowel movements
- Vomiting
Side effects that may not require medical attention include:[2]
- Gas
- Increased bowel movements
- Oily stools
- Upset stomach
Ozempic®
Ozempic® is a medication injected once weekly into the thigh, abdomen, or upper arm. It belongs to a class of medications known as GLP-1 receptor agonists.
These medications mimic a hormone called glucagon-like peptide-1 (GLP-1), which helps regulate blood sugar levels and promote feelings of fullness after eating.
Research suggests that higher doses of semaglutide can produce significant weight loss in people with obesity. In one major study, participants who used semaglutide alongside lifestyle changes lost about 15% of their body weight over 68 weeks—an average of approximately 34 pounds. Participants who did not take the medication lost about six pounds on average.[3]
What Are The Potential Side Effects Of Ozempic®?
Consult a healthcare provider if any of the following side effects occur.
Less common side effects may include:
- Belching
- Bloating
- Gas
- Heartburn
- Stomach discomfort
- Yellowing of the eyes or skin
Rare side effects include:
- Burning sensation in the chest or stomach
- Indigestion
- Stomach upset
- Stomach tenderness
More common side effects may include:
- Diarrhea
Less common side effects include:
- Constipation
- Hair loss
Rare injection-site reactions may include:[4]
- Skin discoloration
- Swelling
- Pain or tenderness at the injection site
- Rash or itching
- Changes in taste
Considering GLP-1 Medications
While medications like orlistat and semaglutide work differently, both may play a role in weight management depending on a person's health history and treatment goals. Prescription GLP-1 medications such as semaglutide are typically prescribed under the guidance of a healthcare provider who can evaluate whether the treatment is appropriate.
If you are exploring medical options for weight management, telehealth programs may connect you with licensed clinicians who can review your health history, discuss treatment options, and determine whether medications such as GLP-1 therapies may be suitable for you.
Related Content
Wegovy® vs. Qysmia® - Everything You Should Know
Contrave® vs. Ozempic® — A Comparison
References
- Weight-loss medications. Mount Sinai. https://www.mountsinai.org/health-library/selfcare-instructions/weight-loss-medicines. Updated on 7/8/2023. Accessed on 9/12/2023.
- Orlistat capsules. Cleveland Clinic. https://my.clevelandclinic.org/health/drugs/19489-orlistat-capsules. Accessed on 9/12/2023.
- Is Ozempic® the answer for weight loss? Cleveland Clinic. https://health.clevelandclinic.org/Ozempic-for-weight-loss/. Published on 3/30/2023. Accessed on 9/12/2023.
- Semaglutide. Mayo Clinic. https://www.mayoclinic.org/drugs-supplements/semaglutide-subcutaneous-route/side-effects/drg-20406730?p=1. 9/23/2023. Updated on 9/1/2023. Accessed on 9/12/2023.
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