OpenClaim

Orlistat Side Effects

The most commonly reported side effects of orlistat include gastrointestinal disorder, rectal discharge, and constipation, based on 27,180 FDA adverse event reports from 2004 to 2025. 10.2% of reports found the drug to be ineffective.

Orlistat side effects

Percentages show how often each reaction appears relative to total reports for orlistat.

1
Drug Ineffective10.2%2,759
2
Gastrointestinal Disorder7.1%1,935
3
Drug Ineffective6.6%1,797
4
Rectal Discharge6.5%1,767
5
Constipation6.2%1,675
6
Weight Increased5.5%1,486
7
Flatulence4.9%1,320
8
Diarrhoea4.5%1,222
9
Abdominal Pain Upper3.5%957
10
Steatorrhoea3.2%877
11
Headache3.2%873
12
Abdominal Distension3.1%846
13
Diarrhoea2.9%788
14
Treatment Noncompliance2.8%765
15
Steatorrhoea2.8%762

These are voluntary reports and do not establish that orlistat caused these reactions.

Report severity

28.5%Serious7,735 reports
10.1%Hospitalizations2,749 reports
1.4%Fatal388 reports

Seriousness is determined by the reporter, not by OpenClaim.

Orlistat drug interactions

Other drugs that appear in adverse event reports alongside orlistat. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Metformin0.7%184
2
Aspirin0.3%95
3
Quetiapine-fumarate0.3%91
4
Ethinyl-estradiol0.3%89
5
Omeprazole0.3%82
6
Adalimumab0.3%78
7
Fluoxetine-hydrochloride0.3%73
8
Atorvastatin-calcium0.3%70
9
Esomeprazole0.2%67
10
Acetaminophen0.2%64
11
Furosemide0.2%64
12
Methotrexate0.2%61
13
Ibuprofen0.2%54
14
Pantoprazole-sodium0.2%54
15
Sodium-oxybate0.2%54

Taken alongside

1
Aspirin2.6%697
2
Metformin2.5%667
3
Acetaminophen2.3%620
4
Levothyroxine-sodium2.1%569
5
Omeprazole1.8%478
6
Furosemide1.8%476
7
Atorvastatin-calcium1.7%451
8
Albuterol1.5%404
9
Simvastatin1.5%398
10
Amlodipine1.5%395
11
Ergocalciferol1.3%361
12
Hydrochlorothiazide1.3%359
13
Insulin1.1%292
14
Lisinopril1.0%267
15
Ibuprofen1.0%259

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports orlistat side effects

62.0% of orlistat adverse event reports involve female patients and 11.2% involve male patients. The largest age group is adult at 84%. These figures reflect who reports side effects, not underlying risk.

Sex

Female62.0%
Male11.2%
Unknown26.8%

Age group

< 20.3%
2–110.3%
12–170.4%
18–6484.0%
65+15.0%

What is orlistat used for

Conditions and purposes for which patients were taking orlistat when the adverse event was reported.

Abnormal FaecesAbnormal Weight GainAccidental ExposureAccidental Exposure To ProductAccidental Exposure To Product By ChildAcneAcute EndocarditisAdjuvant TherapyAge-related Macular DegenerationAlcoholismAnaemiaAngina PectorisAngle Closure GlaucomaAntibiotic ProphylaxisAntibiotic Therapy

Showing 15 of 356 indications

Orlistat brand names and reporting trend

Orlistat is sold under the brand name Xenical.

Brand names

Xenical2,248

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking orlistat with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.