Lotronex Side Effects

See also Warning section.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Stop taking this medication and get medical help right away if any of these very serious side effects occur: constipation, bloody diarrhea/stools, new or worsening stomach/abdominal pain.

This medication may increase serotonin and rarely cause a very serious condition called serotonin syndrome/toxicity. The risk increases if you are also taking other drugs that increase serotonin, so tell your doctor or pharmacist of all the drugs you take (see Drug Interactions section). Get medical help right away if you develop some of the following symptoms: fast heartbeat, hallucinations, loss of coordination, severe dizziness, severe nausea/vomiting/diarrhea, twitching muscles, unexplained fever, unusual agitation/restlessness.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, such as: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
  • bacterial infection
  • viral infection
  • hypothalamic-pituitary insufficiency
  • abnormal sexual function
  • depression
  • photophobia
  • hypertension
  • extrasystoles
  • cardiac arrhythmia
  • hemorrhoids
  • bleeding hemorrhoids
  • hemorrhage
  • pharyngitis
  • sore throat
  • upper respiratory infection
  • sinusitis
  • allergic rhinitis
  • xerostomia
  • gastroesophageal reflux disease
  • gastrointestinal ulcer
  • gastritis
  • dyspepsia
  • ulcerative colitis
  • toxic megacolon
  • ischemic bowel disease
  • ischemic colitis
  • intussusception of intestine
  • ileus
  • fecal impaction
  • gastrointestinal obstruction
  • constipation
  • proctitis
  • urinary tract infection
  • irregular menstrual periods
  • abnormal vaginal bleeding
  • folliculitis
  • acne vulgaris
  • urticaria
  • sedation
  • insomnia
  • fatigue
  • hyperhidrosis
  • dysgeusia
  • parosmia
  • hypesthesia
  • skin rash
  • hyperbilirubinemia
  • headache disorder
  • dyspnea
  • cough
  • nausea
  • flatulence
  • diarrhea
  • increased urinary frequency
  • polyuria
  • abdominal distension
  • abnormal hepatic function tests
  • severe constipation
  • hematoma
  • malaise
  • acute abdominal pain
  • gastrointestinal perforation
  • hypnagogic hallucination
  • symptoms of anxiety
  • tachyarrhythmia

Drug Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (such as prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are: apomorphine, fluvoxamine.

The risk of serious complications of constipation increases if you are also taking other drugs that may cause constipation. Ask your doctor or pharmacist about the safe use of all the products you may take.

The risk of serotonin syndrome/toxicity increases if you are also taking other drugs that increase serotonin. Some examples are street drugs such as MDMA/ "ecstasy," St. John's wort, certain antidepressants (such as SSRIs like fluoxetine/paroxetine, SNRIs like duloxetine/venlafaxine), among others. The risk of serotonin syndrome/toxicity may be more likely when you start or increase the dose of these drugs.