Disclaimer: None of the information in this article constitutes medical advice. All statements are merely the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to prescription medication.
Orlistat is the only FDA-approved weight loss medication that's available over-the-counter (OTC) at the time of updating this article.
Orlistat is the generic name for the medication, and the brand-name versions are Alli and Xenical. We will use these terms interchangeably throughout this article because they refer to the same active drug ingredient.
But is orlistat proven in clinical trials to cause weight loss? And if so, how much? Does the drug cause side effects? And how do real orlistat users rate and describe the effects of the drug?
In this article we'll answer all of these questions and more, as we review clinical studies on orlistat to determine if it's likely to cause weight loss, and if so, how much weight loss the drug can cause.
We'll discuss side effects, document which dose causes the greatest weight loss, feature real patient reviews and explain if the brand-name versions are better.
Does Orlistat Cause Weight Loss?
Orlistat has been studied in a large number of clinical trials for its effects on weight in overweight and obese patients.
A clinical trial published in the Journal of the Academy of Nutrition and Dietetics tested the effects of orlistat in slightly overweight US soldiers.
By the end of the six month trial, the soldiers taking orlistat had lost 2.87 pounds more than those taking placebo pills.
A 2012 clinical trial on orlistat reported more impressive results.
This study included both overweight and obese patients who took orlistat 60 mg milligram (mg) capsules three times daily for 24 weeks along with diet and exercise counseling.
The patients using orlistat lost 15.7% of their visceral fat (fat around organs) compared to visceral fat loss of 9.4% for patients taking placebo pills.
A 2006 clinical trial examined the effects of 16 weeks of orlistat for patients who were categorized as “mildly to moderately overweight."
Patients in this trial were assigned to a restricted calorie diet and supplemented with either orlistat or placebo pills. Both groups lost weight, but the group taking orlistat lost 2.54 pounds more, which if sustained would equate to an annual weight loss of 8.26 pounds more than using diet alone.
Based on the available research, we consider orlistat likely to be effective for weight loss, which is unsurprising given that the drug is approved by the Food and Drug Administration (FDA) for that indication.
Is 120 mg the Best Dose?
All of the studies reviewed in the previous section used an orlistat dose of 60 mg per tablet, but the drug is also prescribed at a dose of 120 mg per tablet.
The branded version of 120 mg orlistat at is called Xenical, and is only available with a prescription.
While we cannot locate any clinical trials directly comparing the weight loss outcomes of orlistat 60 mg versus orlistat 120 mg, this medical review reported that the drug has dose-dependent effects on weight.
This means that the higher the dose, the more weight is lost, which would suggest that orlistat 120 mg is more effective for weight loss than orlistat 60 mg.
The researchers in the above-linked review concluded that orlistat 120 mg “represents the optimal dosage regimen.”
Based on this information, individuals taking OTC versions of orlistat like Alli (which are sold at a 60 mg dose) may benefit from speaking with their doctor about an orlistat 120 mg prescription if they're failing to lose weight.
Real People Try Orlistat
A YouTube creator named "Crazy Cat Paigey" has an orlistat review with over 275,000 views:
A TikTok creator named "NorthernBairnCo" shared her experience after taking orlistat for 14 days:
@thenorthernbairnco Day 14 Orlistat Update #fyp #orlistat #orlistatjourney #weightloss ♬ Boy's a liar Pt. 2 - PinkPantheress & Ice Spice
Does Orlistat Cause Side Effects?
Orlistat does cause side effects in some patients.
The most common side effect is oily stool (medical term “steatorrhea”), but this should be expected because the drug increases the excretion percentage of dietary fats.
A meta-study on orlistat and weight loss reports that patients who keep dietary fat intake under 60 grams (g) daily experience fewer gastrointestinal side effects such as diarrhea and abdominal pain.
The same study documents that there is a rare risk of acute kidney injury because orlistat can increase oxalate production, which is deposited in the kidneys.
The FDA has also reported that orlistat is associated with a small but increased risk of severe liver injury. Only 13 out of over 40 million patients reported experiencing this side effect.
Orlistat doesn't have a "black box" warning on its FDA label at the time of updating this article, which is the most severe category of warning issued by the organization.
Patients Rate Orlistat
Orlistat has been reviewed over 350 times on Drugs.com, which is a website where users of pharmaceutical medication can publish reviews of their experience.
We cannot verify the accuracy or authenticity of any reviews on this site.
Orlistat has an average patient rating of 7.4 out of 10 at the time of updating this article.
The top positive review is written by a user named “Gurlo” who claims the drug was successful for weight loss even without incorporating exercise:
“25, female, started off at 15st 7lbs or 99kg or 217lbs (I’m 5’7). Originally was looking for a quick fix but realistically when it comes to weight loss there isn’t one. I gained 70lbs in the last 4 years and finally realized how unhappy I was. 20 days in and I have lost 14lbs/6kg. I am strict on my diet, though to be honest haven’t done the recommended exercise. So I can only imagine how much I would have lost in that time.”
The top negative review is published by a user named “FairyGardens” who rated the drug 1/10 and claims it was ineffective:
“The new generation of Orlistat, sold over the counter as Alli, does NOT work. I was on Xenical when it first came out in the 1990's. It worked very well and the orange discharge was a daily thing. Now 4 months ago I purchased Alli over the counter. Paid $85 and was very disappointed to find out that I had wasted my money.”
Is the Brand-Name Version Better?
As we’ve referenced multiple times throughout this article, orlistat is the term for the generic version of the drug and the brand-name versions are Alli and Xenical. Alli is the 60 mg OTC version and Xenical is the 120 mg prescription version.
We generally recommend that patients speak with their doctor about the generic form of pharmaceutical drugs, because research shows them to be just as effective as branded drugs but sometimes cheaper.
A medical review published in the PLOS Medicine journal compared the efficacy of generic and branded drugs, and found that there was no difference: “use of generics was associated with comparable clinical outcomes to use of brand-name products.”
Interestingly, the generic version of orlistat is currently more expensive than one of the brand-name versions.
Here are the prices at the time of updating this article, according to GoodRx:
- Orlistat: $555.91
- Xenical: $780.55
- Alli: $67.66
How Does Orlistat Work?
We believe it’s important for patients to understand how drugs they're taking work.
Orlistat’s mechanism of action is to inhibit the production of certain proteins that break down fat consumed in the diet, as documented in a 2022 medical review.
Patients taking orlistat excrete more fat in feces than they would otherwise, which results in a lower percentage of dietary fat being absorbed and metabolized by the body.
The above-linked medical review reports that around 30% less dietary fat is absorbed on orlistat than would be otherwise.
These effects are reversible, and when a patient stops taking orlistat their pancreatic and gastric proteins return to functioning as normal.
Can I Take Orlistat With Antibiotics?
Patients are often curious about whether orlistat can be taken with antibiotics, since weight loss medications are typically taken daily and may overlap with an antibiotic prescription.
Orlistat's FDA label makes no reference that antibiotics are contraindicated, which suggests that users can take orlistat with antibiotics, but it would be good to double-check with a doctor.
The drug's mechanism of action doesn't suggest that there would be a contraindication with antibiotics, because antibiotics are not typically high in fat.
Our Clean Weight Loss Picks
Ceylon cinnamon was described as "an effective anti-obesity agent" in a 2022 meta-analysis. The study authors concluded that effects were greater at doses at or over 3 grams daily.
Illuminate Labs Ceylon Cinnamon Extract is our standardized Ceylon cinnamon supplement which is third-party tested to ensure purity and potency.
Dietary fiber was shown in a medical review published in The Journal of Nutrition to cause 16 pounds of weight loss in 6 months when combined with moderate caloric restriction (750 calories per day below baseline).
MBG Organic Fiber Potency+ is our top fiber pick because it's certified organic, provides 7 g of fiber per serving and costs under $1.85 per serving at the time of updating this article.
Both of the products mentioned in this section are entirely free of additive ingredients that we consider to be unhealthy.
We are not suggesting that the products referenced in this section are as effective as orlistat, or any other FDA-approved weight loss medication. Rather, we're sharing options that patients with an aversion to pharmaceutical medication may wish to speak to their doctor about.
