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Compare Alli vs. Wegovy

Head-to-head comparisons of medication uses, side effects, warnings, and more.

Key takeaways

Orlistat (Xenical, Alli) and semaglutide (Wegovy) are both medications used to help with weight loss in people with overweight or obesity. However, they belong to different medication classes and work in different ways. Orlistat is a lipase inhibitor that blocks the absorption of fats from your diet, while semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist that helps control your appetite and makes you feel full sooner. Orlistat is available both over-the-counter (as Alli) and by prescription (as Xenical), and you take it three times a day with meals. Semaglutide, on the other hand, is a prescription-only medication that you inject under your skin once a week. Orlistat can cause side effects like oily stools and gas, while semaglutide may cause nausea, vomiting and diarrhea. Additionally, orlistat can interact with medications like levothyroxine (Synthroid, Levoxyl, Tirosint) and warfarin (Coumadin, Jantoven); semaglutide can affect how these medications are absorbed and also had an increased risk of low blood sugar when combined with other diabetes medications.

Orlistat
Wegovy (semaglutide)
Orlistat
Wegovy (semaglutide)
Summary of Alli vs. Wegovy
Summary for Lipase inhibitor
Orlistat is a medication that works alongside diet and exercise to increase weight loss in people who are overweight or obese. It needs to be taken three times a day and is available with a prescription in a higher dose (Xenical) or over the counter in a lower dose (Alli).
Summary for GLP-1 agonist
Prescription only
Wegovy (semaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist. It comes in prefilled pens you use to inject the medication under the skin once a week. Wegovy (semaglutide) also comes as tablets that are swallowed once a day. This medication is approved for weight loss in some people. It can help lower the risk of heart attack, stroke, and death due to heart problems in adults with a larger body size and heart disease. The pens are also approved for certain adults with a liver problem called metabolic dysfunction-associated steatohepatitis (MASH). The medication works best when taken with a lower-calorie diet and regular exercise. Side effects include nausea, diarrhea, and stomach pain.
Indications of Alli vs. Wegovy
Indications for
Xenical (orlistat):

•Obesty management in adults with a body mass index (BMI) of:

•30 kg/m^2^ or greater or

•27 kg/m^2^ or greater and at least one weight-related condition (e.g., high blood pressure, type 2 diabetes, or high cholesterol)

Alli (orlistat):

•Weight loss in adults when combined with a lower-calorie and low-fat diet

Indications for
Injectable pens:

•
Weight loss and long-term weight management in:

•People ages 12 years and older who are considered obese

•Adults considered overweight with at least one weight-related condition (e.g., high blood pressure, Type 2 diabetes, high cholesterol)

•
Lowering the risk of heart attack, stroke, and death due to heart problems in adults with a larger body size and heart disease

•
Metabolic dysfunction-associated steatohepatitis (MASH) in adults with moderate-to-advanced liver scarring, but not cirrhosis

Tablets:

•Weight loss and long-term weight management in adults who are considered obese or overweight with at least one weight-related condition

•Lowering the risk of heart attack, stroke, and death due to heart problems in adults with a larger body size and heart disease
Pros and Cons of Alli vs. Wegovy
Pros and Const for Lipase inhibitor
Pros

•Works well to block a portion of the fat you eat

•Xenical is approved for people ages 12 years and older.

•Available in both prescription and over-the-counter forms

Cons

•Still need to maintain a healthy diet and exercise routine

•Must remember to take with each fat-containing meal

•Only available as a brand medication so it can be expensive

Pros and Const for GLP-1 agonist
Pros

•Available as once-weekly injectable pens and as once-daily pills

•Injectable pens approved for weight loss in children ages 12 years and older considered obese

Cons

•Can cause stomach pain, nausea, and diarrhea

•Can't take with other semaglutide products (Ozempic, Rybelsus) or with other GLP-1 agonists
Common Side Effects of Alli vs. Wegovy
Common Side Effects for
Xenical (orlistat):

•Oily spotting on underwear (4-27%)

•Gas with anal discharge (2-24%)

•Urge to have a bowel movement (3-22%)

•Fatty or oily stool (6-20%)

•Having more bowel movements (3-11%)

•Difficulty controlling bowel movements (2-8%)

Alli (orlistat):

•Gas with oily spotting

•Loose stools

•More frequent stools that are hard to control

Common Side Effects for

•Nausea (44%)

•Diarrhea (30%)

•Vomiting (24%)

•Constipation (24%)

•Stomach pain (20%)

•Headache (14%)

•Tiredness (11%)
Warnings of Alli vs. Wegovy
Common Side Effects for

•Medication interactions

•Liver injury

•Higher oxalate levels in the urine

•Gallstones

•Other causes of obesity

Common Side Effects for

•Possible risk for thyroid cancer

•Inflammation of the pancreas (pancreatitis)

•Gallbladder problems

•Low blood sugar

•Kidney damage

•Allergic reactions

•Eye problems in people with Type 2 diabetes (diabetic retinopathy)

•Faster heart rate

•Possible risk of self-harm

•Lung problems during general anesthesia or deep sedation
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Key takeaways

Summary of Alli vs. Wegovy

Indications of Alli vs. Wegovy

Pros and Cons of Alli vs. Wegovy

Common Side Effects of Alli vs. Wegovy

Warnings of Alli vs. Wegovy

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