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Lotronex Side Effects

Generic Name: alosetron

Note: This page contains information about the side effects of alosetron. Some of the dosage forms included on this document may not apply to the brand name Lotronex.

Not all side effects for Lotronex may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to alosetron: oral tablet

In addition to its needed effects, some unwanted effects may be caused by alosetron (the active ingredient contained in Lotronex). In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking alosetron:

More common
  • Constipation
  • Bloody diarrhea
  • new or worsening stomach pain or discomfort
  • rectal bleeding
Incidence not known
  • Abdominal or stomach pain, cramping, or burning
  • black, tarry stools
  • diarrhea
  • fever
  • heartburn
  • indigestion
  • nausea
  • vomiting with or without blood or material that looks like coffee grounds

If any of the following symptoms of overdose occur while taking alosetron, get emergency help immediately:

Symptoms of overdose
  • Clumsiness, unsteadiness, trembling, or other problems with muscle control or coordination
  • convulsions (seizures)
  • difficulty breathing
  • shakiness and unsteady walk
  • withdrawn or socially detached behavior

Some of the side effects that can occur with alosetron may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Less common
  • Bleeding after bowel movement
  • full or bloated feeling
  • pressure in the stomach
  • swelling of abdominal or stomach area
  • uncomfortable swelling around rectal area
Incidence not known
  • Headache
  • skin rash

For Healthcare Professionals

Applies to alosetron: oral tablet


In IBS clinical trials, the incidence of serious complications of constipation in women was approximately 1 per 1,000 patients, but approximately 10% of patients on alosetron (the active ingredient contained in Lotronex) withdrew prematurely because of constipation.[Ref]

Gastrointestinal side effects have included constipation as the most common side effect. It has been reported in 29% of treated patients versus 6% for placebo. In IBS clinical trials, the cumulative incidence of ischemic colitis in women was 2 per 1,000 patients over 3 months, and 3 per 1,000 patients over 6 months. Other GI side effects have included abdominal discomfort and pain (7% vs. 4% for placebo), nausea (6% vs. 5% for placebo), GI discomfort and pain (5% vs. 3% for placebo), hemorrhoids (2% to 3%), hemorrhoidal hemorrhage (2% to 3%), diarrhea (2% to 3%), flatulence (1% to 3%), and upper abdominal pain (1% to 3%), abdominal distention (2% vs. 1% for placebo), and regurgitation and reflux (2% vs. 2% for placebo). Postmarketing surveillance side effects have also included ileus, impaction, obstruction, perforation, ulceration, and small bowel mesenteric ischemia.[Ref]

Nervous system

Nervous system side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of hypnagogic effects. Memory effects, tremors, dreams, cognitive function disorders, disturbances of sense of taste, disorders of equilibrium, confusion, sedation, and hypoesthesia have been reported rarely (fewer than 1 in 1,000 patients). Postmarketing reports have included headache.[Ref]


Cardiovascular side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of tachyarrhythmias and rare (fewer than 1 in 1,000 patients) reports of arrhythmias, increased blood pressure and extrasystoles.[Ref]


Psychiatric side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of anxiety and rare (less than 1 in 1,000 patients) reports of depressive disorders.[Ref]


Hepatic side effects have included reports of ALT elevations greater than 2 fold in 1% of treated patients compared to 1.2% with placebo. Abnormal bilirubin levels and cholecystitis have been reported rarely. A single case of hepatitis has been reported.[Ref]


Other side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of malaise, fatigue, cramps, pain, and temperature regulation disturbances.[Ref]


Respiratory side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of breathing disorders. Viral respiratory infections have been reported rarely (1 in 1,000 patients).[Ref]


Genitourinary side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of urinary frequency and rare (fewer than 1 in 1,000 patients) reports of bladder inflammation, polyuria, diuresis, and sexual function disorders.[Ref]


Dermatologic side effects have included infrequent (1 in 100 to 1 in 1,000 patients) reports of sweating and urticaria, and rare (fewer than 1 in 1,000 patients) reports of hair loss and alopecia; acne and folliculitis; sweat and sebum disorders; allergic skin reactions; eczema; skin infections; dermatitis and dermatosis; and nail disorders. Postmarketing reports have included rash.[Ref]


Ocular side effects have included photophobia (less than 0.1%).[Ref]


Musculoskeletal side effects have rarely included muscle pain, muscle stiffness, tightness and rigidity, and bone and skeletal pain.[Ref]


Hematologic side effects have been reported rarely. These have included quantitative red cell or hemoglobin defects, hemorrhage, and lymphatic signs and symptoms.[Ref]


1. Avigan M, Justice R, Mackey AC, Nair N "Re: Brandt et al.--An evidence-based approach to the management of irritable bowel syndrome in North America." Am J Gastroenterol 98 (2003): 2105-6

2. Miller DP, Alfredson T, Cook SF, Sands BE, Walker AM "Incidence of colonic ischemia, hospitalized complications of constipation, and bowel surgery in relation to use of alosetron hydrochloride." Am J Gastroenterol 98 (2003): 1117-22

3. "Product Information. Lotronex (alosetron)." Glaxo Wellcome, Research Triangle Park, NC.

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