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Rilutek Side Effects

Generic Name: riluzole

Note: This document contains side effect information about riluzole. Some of the dosage forms listed on this page may not apply to the brand name Rilutek.

In Summary

Common side effects of Rilutek include: asthenia, nausea, and increased serum alanine aminotransferase. Other side effects include: vomiting. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to riluzole: oral tablet

Along with its needed effects, riluzole (the active ingredient contained in Rilutek) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking riluzole:

Less common

  • Bladder pain
  • bloody or cloudy urine
  • blurred vision
  • dark urine
  • difficult, burning, or painful urination
  • fast, pounding, or irregular heartbeat or pulse
  • flu-like symptoms
  • frequent urge to urinate
  • headache
  • increased cough
  • itching skin
  • lower back or side pain
  • nervousness
  • persistent anorexia
  • pounding in the ears
  • right upper quadrant tenderness
  • slow heartbeat
  • yellow eyes or skin

Incidence not known

  • Black, tarry, stools
  • chills
  • cough
  • decreased frequency or amount of urine
  • difficult breathing
  • fever
  • increased thirst
  • loss of appetite
  • nausea
  • pale skin
  • sore throat
  • swelling of the face, fingers, or lower legs
  • ulcers, sores, or white spots in the mouth
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vomiting
  • weight gain

Some side effects of riluzole may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Lack or loss of strength

Less common

  • Abdominal or stomach pain
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • difficulty moving
  • dizziness or lightheadedness
  • dry mouth
  • excess air or gas in the stomach or intestines
  • feeling of constant movement of self or surroundings
  • full feeling
  • muscle pain or stiffness
  • pain in the joints
  • passing gas
  • rapid weight gain
  • sensation of spinning
  • skin rash, encrusted, scaly and oozing
  • sleepiness or unusual drowsiness
  • tingling of the hands or feet
  • trouble sleeping
  • unusual weight gain or loss

For Healthcare Professionals

Applies to riluzole: oral tablet


At least one elevation in ALT has occurred in 50% of patients receiving riluzole (the active ingredient contained in Rilutek) An ALT greater than 5 times the upper limit of normal has occurred in approximately 2% of patients. These elevations tend to occur within the first 3 months of treatment, are usually transient if less than 5 times the upper limit of normal, and may return to normal within 2 to 6 months if therapy is continued. There is little experience in the management of patients whose ALT exceeds 5 times the upper limit of normal. The manufacturer recommends discontinuing the drug if ALT exceeds 10 times the upper limit of normal or if jaundice occurs.

In one patient receiving riluzole for epilepsy and concurrently taking phenobarbital and carbamazepine, clinical jaundice developed four months after starting riluzole (ALT 26 X ULN, AST 17 X ULN, and bilirubin 11 X ULN). Liver function tests returned to normal 7 weeks after discontinuing riluzole therapy.[Ref]

Hepatic side effects including elevations in alanine aminotransferase (ALT), aspartate aminotransferase (AST), and jaundice have been reported. Cases of clinical hepatitis associated with riluzole have been reported, including one with a fatal outcome.[Ref]


Most gastrointestinal side effects have been dose-related. Nausea and abdominal pain commonly resulted in discontinuation of riluzole (the active ingredient contained in Rilutek) during clinical trials.[Ref]

Gastrointestinal side effects have included nausea (16.3%), abdominal pain (5.1%), vomiting (4.2%), anorexia (3.2%), and diarrhea (2.9%). Two cases of pancreatitis have also been reported.[Ref]


Musculoskeletal side effects including asthenia (which appears to be dose-related) (19.2%) and muscle stiffness have been reported.[Ref]


Respiratory side effects including cases of interstitial lung disease have been reported in patients treated with riluzole (the active ingredient contained in Rilutek) some of them severe. Upon further investigation, many of these cases were hypersensitivity pneumonitis.

Nervous system

Nervous system side effects appear to be dose-related. Dizziness occurred more frequently in female patients.[Ref]

Nervous system side effects including dizziness (3.8%), vertigo (1.9%), circumoral paresthesias (1.6%) and somnolence (1.9%) have been reported.[Ref]


Hematologic side effects including anemia and neutropenia (absolute neutrophil count less than 500/mm3) have rarely been reported. A case of methemoglobinemia has also been reported.[Ref]


Cardiovascular side effects including mild to moderate increases in blood pressure have been reported.[Ref]


Hypersensitivity side effects including anaphylaxis have been reported.


1. Bensimon G, Lacomblez L, Meininger V "A controlled trial of riluzole in amyotrophic lateral sclerosis. ALS/Riluzole Study Group." N Engl J Med 330 (1994): 585-91

2. "Product Information. Rilutek (riluzole)." Rhone-Poulenc Rorer, Collegeville, PA.

3. Rodrigo L, Moreno M, Calleja S, Mateos V, Andrade RJ, Lucena MI "Riluzole-induced acute pancreatitis." Am J Gastroenterol 96 (2001): 2268-9

4. Drory VE, Sidi I, Korczyn AD "Riluzole-induced pancreatitis." Neurology 52 (1999): 892-3

5. Weber G, Bitterman H "Riluzole-induced neutropenia." Neurology 62 (2004): 1648

6. Woolf A, Carstairs SD, Tanen DA "Riluzole-induced methemoglobinemia." Ann Emerg Med 43 (2004): 294

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.