Orlistat Side Effects

Brand Names: Alli, Xenical

Please note - some side effects for Orlistat may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Orlistat - for the consumer

Orlistat

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Orlistat:

Diarrhea; frequent or loose stools; gas with discharge; oily spotting; trouble controlling bowel movements.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); severe or persistent stomach pain.

By body system

General side effects

In general, the adverse effects of orlistat are mild and transient. Because the drug is not systemically absorbed, most adverse effects are limited to the gastrointestinal tract and are primarily extensions of the pharmacologic activity of the drug.

Gastrointestinal side effects

Gastrointestinal (GI) side effects including oily spotting, flatus with discharge, fecal urgency, fatty or oily stool, oily evacuation, increased defecation, and fecal incontinence have been reported in greater than or equal to 5% of patients. Cholelithiasis has been reported in 2.9% of patients versus 1.8% in placebo. Other GI side effects possibly related to orlistat treatment have included abdominal pain and discomfort, nausea, infectious diarrhea, rectal pain and discomfort, tooth disorder, gingival disorder, and vomiting. At least one case of constipation has been reported. Pancreatitis has also been reported during postmarketing experience.

During clinical trials, approximately half of all incidents of GI adverse events associated with orlistat treatment lasted less than one week, and a majority lasted for no more than four weeks. However, these side effects may occur in some persons over a period of 6 months or longer.

A 42-year-old female experienced constipation, polyuria, polydipsia, and increased lower-leg edema after 2 weeks of treatment with orlistat 120 mg 3 times daily. After the drug was discontinued for 4 days, the symptoms resolved. On reinstitution of the orlistat therapy, the symptoms reappeared within 2 days. Thereafter, the drug was permanently discontinued.

Hypersensitivity side effects

Hypersensitivity side effects have rarely included pruritus, rash, urticaria, angioedema, bronchospasm, and anaphylaxis. At least one case of cutaneous leukocytoclastic vasculitis has also been reported.

A 34-year-old male with a history of obesity experienced cutaneous leukocytoclastic vasculitis coincident with orlistat therapy. He decided to take orlistat (120 mg before meals) as medical therapy for obesity. Seventy-two hours after the onset of this treatment, he experienced myalgias and arthralgias. He also observed the presence of maculopapular lesions in rapidly increasing numbers in his lower extremities. A skin biopsy revealed leukocytoclastic vasculitis affecting capillaries and venules. Orlistat was discontinued and bed rest and nonsteroidal anti-inflammatory drugs were prescribed. Following initiation of this procedure, a rapid improvement of the cutaneous lesions was attained.

Respiratory side effects

Respiratory side effects have included influenza, upper respiratory infection, lower respiratory infection, and ear, nose and throat symptoms.

Musculoskeletal side effects

Musculoskeletal side effects have included back pain, pain in the lower extremities, arthritis, myalgia, joint disorder, and tendonitis.

Nervous system side effects

Nervous system side effects have included headache and dizziness.

Dermatologic side effects

Dermatologic side effects have included rash and dry skin. Rare cases of bullous eruptions have been reported during postmarketing experience.

Genitourinary side effects

Genitourinary side effects have included menstrual irregularities and vaginitis. Urinary tract infection has also been reported.

Psychiatric side effects

Psychiatric side effects have included psychiatric anxiety and depression.

Cardiovascular side effects

Cardiovascular side effects have included pedal edema. At least one case of hypertension has also been reported.

A 40-year-old previously healthy female experienced hypertension coincident with orlistat therapy. She took sporadic doses for some months and then increased the dosage to 120 mg three times a day. She experienced dizziness, peripheral edema, and pulsating headache and discontinued treatment. On medical examination, her blood pressure was 190/100 mm Hg on three different measurements. She was advised to discontinue orlistat, and a few days later her blood pressure had decreased to 160/90 mm Hg and the edema had regressed.

Hematologic side effects

Hematologic side effects have included decreased prothrombin, increased INR, and unbalanced anticoagulant treatment with changes of hemostatic parameters in patients treated concomitantly with orlistat and anticoagulants.

Metabolic side effects

Metabolic side effects have included hypoglycemia in clinical trials of obese diabetic patients. At least one case of diabetic ketoacidosis has also been reported, in addition to a case of polyuria and polydipsia.

An 18-year-old female with type 1 diabetes for the past 3 years experienced diabetic ketoacidosis coincident with orlistat therapy. She presented to the hospital after she began taking, on her own, orlistat 120 mg three times per day in addition to a low-calorie diet. Laboratory data showed severe ketosis and positive urinary ketones. Orlistat was discontinued, and she was started on intravenous hydration and insulin. She showed significant improvement over a period of 5 days.

A 42-year-old female experienced constipation, polyuria, polydipsia, and increased lower-leg edema after 2 weeks of treatment with orlistat 120 mg 3 times daily. After the drug was discontinued for 4 days, the symptoms resolved. On reinstitution of the orlistat therapy, the symptoms reappeared within 2 days. Thereafter, the drug was permanently discontinued.

Hepatic side effects

A 15-year-old female without a remarkable medical history experienced severe hepatic injury coincident with orlistat therapy. She had taken orlistat 120 mg three times daily for 7 days for obesity. One week later, she was admitted to an emergency hospital with abdominal pain, malaise, nausea, and diarrhea. Her serum aspartate aminotransferase and alanine aminotransferase levels were surprisingly high at 8269 intl units/L and 9976 intl units/L, respectively. She was given vitamin K intravenously for 5 days, and liver function tests results normalized within 1 month.

Hepatic side effects have included very rare reports of increase in transaminases and in alkaline phosphatase, and exceptional cases of hepatitis. No causal relationship or physiopathological mechanism between hepatitis and orlistat therapy has been established. At least one case of severe hepatic injury has also been reported.

Renal side effects

A 57-year-old female with underlying chronic kidney disease experienced acute kidney injury secondary to acute oxalate nephropathy coincident with orlistat therapy. Acute kidney injury was associated temporally with an increased dosage of orlistat therapy and the development of increased fat malabsorption. Kidney biopsy indicated deposition of calcium oxalate crystals within tubular lumens, consistent with acute oxalate crystals within tubules. A steady improvement in renal function was subsequently observed. Results of a repeated 24-hour urine oxalate collection performed 3 weeks later when kidney function had improved were within normal parameters.

Renal side effects including at least one case of acute oxalate nephropathy have been reported.

Other side effects

Other side effects have included fatigue, otitis, and sleep disorders.

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