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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.

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.

Major Side Effects

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  • withdrawn or socially detached behavior

Minor Side Effects

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


-Very common (10% or more): Constipation (up to 29%)
-Common (1% to 10%): Abdominal discomfort/pain, diarrhea, nausea, GI discomfort/pain, abdominal distention, regurgitation/reflux, hemorrhoids, hemorrhoidal hemorrhage, viral gastroenteritis, flatulence
-Uncommon (0.1% to 1%): Ischemic colitis, hyposalivation, dyspeptic symptoms, GI spasms, GI lesions, serious constipation complications (obstruction, ileus, impaction, toxic megacolon, secondary bowel ischemia)
-Rare (less than 0.1%): Abnormal tenderness, colitis, proctitis, diverticulitis, positive fecal occult blood, hyperacidity, decreased GI motility and ileus, GI obstructions, oral symptoms, GI intussusception, gastritis, gastroduodenitis, gastroenteritis, ulcerative colitis
-Postmarketing reports: Impaction, ulceration, small bowel mesenteric ischemia, serious constipation complications (perforation, death)[Ref]


-Uncommon (0.1% to 1%): Tachyarrhythmia
-Rare (less than 0.1%): Arrhythmia, increased blood pressure, extrasystoles, contusion, hematoma[Ref]


-Uncommon (0.1% to 1%): Sweating, urticaria
-Rare (less than 0.1%): Hair loss/alopecia, acne/folliculitis, sweat and sebum disorders, allergic skin reaction, eczema, skin infections, dermatitis/dermatosis, nail disorders
-Postmarketing reports: Rash[Ref]


Rare (less than 0.1%): Hypothalamus and pituitary hypofunction[Ref]


-Common (1% to 10%): Urinary tract infection, urinary frequency
-Rare (less than 0.1%): Female reproductive tract bleeding and hemorrhage, reproductive infections, fungal reproductive infections, bladder inflammation, polyuria/diuresis, urinary tract hemorrhage[Ref]


Rare (less than 0.1%): Quantitative red cell or hemoglobin defects, hemorrhage[Ref]


-Common (1% to 10%): More than 2-fold elevation of ALT
-Rare (less than 0.1%): Abnormal bilirubin levels, cholecystitis
-Very rare (less than 0.01%): Hepatitis (elevated ALT, AST, alkaline phosphatase, and bilirubin)[Ref]


-Rare (less than 0.1%): Calcium and phosphate metabolism disorders, hyperglycemia, hypoglycemia, fluid disturbance[Ref]


-Common (1% to 10%): Muscle spasms
-Rare (less than 0.1%): Muscle pain, muscle stiffness, tightness/rigidity, bone/skeletal pain[Ref]

Nervous system

-Common (1% to 10%): Headache
-Rare (less than 0.1%): Memory effects, tremors, dreams, cognitive function disorders, taste disturbances, equilibrium disorders, confusion, sedation, hypoesthesia, burning sensations, hot and cold sensations[Ref]


Rare (less than 0.1%): Light sensitivity of eyes[Ref]


-Common (1% to 10%): Malaise/fatigue
-Uncommon (0.1% to 1%): Cramps, pain, temperature regulation disturbances, fungal infections[Ref]


-Uncommon (0.1% to 1%): Hypnagogic effects
-Rare (less than 0.1%): Depressive moods, sexual function disorders[Ref]


-Common (1% to 10%): Upper respiratory tract infection, nasopharyngitis, sinusitis, cough
-Uncommon (0.1% to 1%): Breathing disorders
-Rare (less than 0.1%): Ear/nose/throat infection (viral and non-viral), laryngitis[Ref]


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

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.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.