February 14, 2016
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Side Effects


The most commonly observed AEs associated with the use of RILUTEK (riluzole) more frequently than placebo treated patients were: asthenia, nausea, dizziness, decreased lung function, diarrhea, abdominal pain, pneumonia, vomiting, vertigo, circumoral paresthesia, anorexia, and somnolence. Asthenia, nausea, dizziness, diarrhea, anorexia, vertigo, somnolence, and circumoral paresthesia were dose related.

Approximately 14% (n = 141) of the 982 individuals with ALS who received RILUTEK (riluzole) in premarketing clinical trials discontinued treatment because of an adverse experience. Of those patients who discontinued due to adverse events, the most commonly reported were: nausea, abdominal pain, constipation, and ALT elevations. In a dose response study in ALS patients, the rates of discontinuation of RILUTEK (riluzole) for asthenia, nausea, abdominal pain, and ALT elevation were dose related.

Incidence in Controlled ALS Clinical Studies

Table 1 lists treatment-emergent signs and symptoms that occurred in at least 2% of patients with ALS treated with RILUTEK (riluzole) (n=794) participating in placebo-controlled trials and were numerically greater in the patients treated with RILUTEK (riluzole) 100 mg/day than with placebo or for which a dose response relationship is suggested.

The prescriber should be aware that these figures cannot be used to predict the frequency of adverse experiences in the course of usual medical practice where patient characteristics and other factors may differ from those prevailing during clinical studies. Inspection of these frequencies, however, does provide the prescriber with one basis to estimate the relative contribution of drug and non-drug factors to the AE incidences in the population studied.

Table 1: Adverse Events Occurring in Placebo-Controlled Clinical Trials

Body System /
Adverse Event
Percentage of patients reporting events
50 mg/day
100 mg/day
200 mg/day
Body as a Whole
  Asthenia 14.8 19.2 20.1 12.2
  Headache 8.0 7.3 7.0 6.6
  Abdominal pain 6.8 5.1 7.8 3.8
  Back pain 1.7 3.2 4.1 2.5
  Aggravation reaction 0.4 1.3 2.0 0.9
  Malaise 0.4 0.6 1.2 0.0
  Nausea 12.2 16.3 20.5 10.6
  Vomiting 4.2 4.2 4.5 1.6
  Dyspepsia 2.5 3.8 6.1 5.0
  Anorexia 3.8 3.2 8.6 3.8
  Diarrhea 5.5 2.9 9.0 3.1
  Flatulence 2.5 2.6 2.0 1.9
  Stomatitis 0.8 1.0 1.2 0.0
  Tooth disorder 0.0 1.0 1.2 0.3
  Oral Moniliasis 0.4 0.6 1.2 0.3
  Hypertonia 5.9 6.1 5.3 5.9
  Depression 4.2 4.5 6.1 5.0
  Dizziness 5.1 3.8 12.7 2.5
  Dry mouth 3.0 3.5 2.0 3.4
  Insomnia 2.1 3.5 2.9 3.4
  Somnolence 0.8 1.9 4.1 1.3
  Vertigo 2.5 1.9 4.5 0.9
  Circumoral paresthesia 1.3 1.6 3.3 0.0
Skin and Appendages
  Pruritus 3.8 3.8 2.5 3.1
  Eczema 0.8 1.6 1.6 0.6
  Alopecia 0.0 1.0 1.2 0.6
  Exfoliative dermatitis 0.0 0.6 1.2 0.0
  Decreased lung function 13.1 10.2 16.0 9.4
  Rhinitis 8.9 6.4 7.8 6.3
  Increased cough 2.1 2.6 3.7 1.6
  Sinusitis 0.4 1.0 1.6 0.9
  Hypertension 6.8 5.1 3.3 4.1
  Tachycardia 1.3 2.6 2.0 1.3
  Phlebitis 0.4 1.0 0.8 0.3
  Palpitation 0.4 0.6 1.2 0.9
  Postural hypotension 0.8 0.0 1.6 0.6
Metabolic and Nutritional Disorders
  Weight loss 4.6 4.8 3.7 4.7
  Peripheral edema 4.2 2.9 3.3 2.2
Musculoskeletal System
  Arthralgia 5.1 3.5 1.6 3.4
Urogenital System
  Urinary tract infection 2.5 2.6 4.5 2.2
  Dysuria 0.0 1.0 1.2 0.3

Other Adverse Events Observed

Other events which occurred in more than 2% of patients treated with RILUTEK (riluzole) 100 mg/day but equally or more frequently in the placebo group included: accidental injury, apnea, bronchitis, constipation, death, dysphagia, dyspnea, flu syndrome, heart arrest, increased sputum, pneumonia, and respiratory disorder.

The overall adverse event profile for RILUTEK (riluzole) was similar between females and males, and was independent of age. Because the largest non-white racial subgroup was only 2% of patients exposed to RILUTEK (riluzole) (18/794) in placebo-controlled trials, there are insufficient data to support a statement regarding the distribution of adverse experience reports by race. In ALS studies, dizziness did occur more commonly in females (11%) than in males (4%). There was not a difference between females and males in the rates of discontinuation of RILUTEK (riluzole) for individual adverse experiences.

Other Adverse Events Observed During All Clinical Trials

RILUTEK (riluzole) has been administered to 1713 individuals during all clinical trials, some of which were placebo-controlled. During these trials, all adverse events were recorded by the clinical investigators using terminology of their own choosing. To provide a meaningful estimate of the proportion of individuals having adverse events, similar types of events were grouped into a smaller number of standardized categories using modified COSTART dictionary terminology. The frequencies presented represent the proportion of the 1713 individuals exposed to RILUTEK (riluzole) who experienced an event of the type cited on at least one occasion while receiving RILUTEK (riluzole) . All reported events are included except those already listed in the previous table, those too general to be informative, and those not reasonably associated with the use of the drug. Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring in at least 1/100 patients; infrequent adverse events are those occurring in 1/100 to 1/1000 patients; rare adverse events are those occurring in fewer than 1/1000 patients.

* = AE frequency ≤ to placebo

Body as a Whole: Frequent: Hostility*. Infrequent: Abscess*, sepsis*, photosensitivity reaction*, cellulitis, face edema*, hernia, peritonitis, attempted suicide, injection site reaction, chills*, flu syndrome, intentional injury, enlarged abdomen, neoplasm. Rare: Acrodynia, hypothermia, moniliasis*, rheumatoid arthritis.

Digestive System: Infrequent: Increased appetite, intestinal obstruction*, fecal impaction, gastrointestinal hemorrhage, gastrointestinal ulceration, gastritis*, fecal incontinence, jaundice, hepatitis, glossitis, gum hemorrhage*, pancreatitis, tenesmus, esophageal stenosis. Rare: Cheilitis*, cholecystitis, hematemesis, melena*, biliary pain, proctitis, pseudomembranous enterocolitis, enlarged salivary gland, tongue discoloration, tooth caries.

Immune System Disorders: Infrequent: Anaphylactoid reaction and anaphylaxis.

Nervous System: Frequent: Agitation*, tremor. Infrequent: Hallucinations, personality disorder*, abnormal thinking*, coma, paranoid reaction*, manic reaction, ataxia, extrapyramidal syndrome, hypokinesia, urinary retention, emotional lability, delusions, apathy, hypesthesia, incoordination, confusion*, convulsion, leg cramps, amnesia, dysarthria, increased libido, stupor, subdural hematoma, abnormal gait, delirium, depersonalization, facial paralysis, hemiplegia, decreased libido, myoclonus. Rare: Abnormal dreams, acute brain syndrome, CNS depression, dementia, cerebral embolism, euphoria*, hypotonia, ileus*, peripheral neuritis, psychosis*, psychotic depression, schizophrenic reaction, trismus, wristdrop.

Skin and Appendages: Infrequent: Skin ulceration, urticaria, psoriasis, seborrhea*, skin disorder, fungal dermatitis*. Rare: Angioedema, contact dermatitis, erythema multiforme, furunculosis*, skin moniliasis, skin granuloma, skin nodule.

Respiratory System: Infrequent: Hiccup, pleural disorder*, asthma, epistaxis, hemoptysis, yawn, hyperventilation*, lung edema*, hypoventilation*, lung carcinoma, hypoxia, laryngitis, pleural effusion, pneumothorax*, respiratory moniliasis, stridor.

Cardiovascular System: Infrequent: Syncope*, hypotension, heart failure, migraine, peripheral vascular disease, angina pectoris*, myocardial infarction*, ventricular extrasystoles, cerebral hemorrhage, atrial fibrillation*, bundle branch block, congestive heart failure, pericarditis, lower extremity embolus, myocardial ischemia*, shock*. Rare: Bradycardia, cerebral ischemia, hemorrhage, mesenteric artery occlusion, subarachnoid hemorrhage, supraventricular tachycardia*, thrombosis, ventricular fibrillation, ventricular tachycardia.

Metabolic and Nutritional Disorders: Infrequent: Gout*, respiratory acidosis, edema, thirst*, hypokalemia, hyponatremia, weight gain*. Rare: Generalized edema, hypercalcemia, hypercholesteremia.

Endocrine System: Infrequent: Diabetes mellitus, thyroid neoplasia. Rare: Diabetes insipidus, parathyroid disorder.

Hemic and Lymphatic System: Infrequent: Anemia*, leukocytosis, leukopenia, ecchymosis. Rare: Neutropenia, aplastic anemia, cyanosis, hypochromic anemia, iron deficiency anemia, lymphadenopathy, petechiae*, purpura.

Musculoskeletal System: Infrequent: Arthrosis, myasthenia*, bone neoplasm. Rare: Bone necrosis, osteoporosis, tetany.

Special Senses: Infrequent: Amblyopia, ophthalmitis. Rare: Blepharitis, cataract, deafness, diplopia*, ear pain, glaucoma, hyperacusis, photophobia, taste loss, vestibular disorder.

Urogenital System: Infrequent: Urinary urgency, urine abnormality, urinary incontinence, kidney calculus, hematuria, impotence, prostate carcinoma, kidney pain, metrorrhagia, priapism. Rare: Amenorrhea, breast abscess, breast pain, nephritis*, nocturia, pyelonephritis, enlarged uterine fibroids, uterine hemorrhage, vaginal moniliasis.

Laboratory Tests: Infrequent: Increased gamma glutamyl transferase, abnormal liver function/tests, increased alkaline phosphatase, positive direct Coombs test, increased gamma globulins. Rare: increased lactic dehydrogenase.

* = AE frequency ≤ to placebo

Read the Rilutek (riluzole) Side Effects Center for a complete guide to possible side effects


There have been no clinical studies designed to evaluate the interaction of riluzole with other drugs.

As with all drugs, the potential for interaction by a variety of mechanisms is a possibility.

Hepatotoxic Drugs

The clinical trials in ALS excluded patients on concomitant medications which were potentially hepatotoxic, (e.g., allopurinol, methyldopa, sulfasalazine). Accordingly, there is no information about the safety of administering RILUTEK (riluzole) in conjunction with such medications. If the practitioner chooses to prescribe such a combination, caution should be exercised.

Drugs Highly Bound To Plasma Proteins

Riluzole is highly bound (96%) to plasma proteins, binding mainly to serum albumin and to lipoproteins. The effect of riluzole (up to 5 mcg/mL) on warfarin (5 mcg/mL) binding did not show any displacement of warfarin. Conversely, riluzole binding was unaffected by the addition of warfarin, digoxin, imipramine and quinine at high therapeutic concentrations.

Effect of Other Drugs On Riluzole Metabolism

In vitro studies using human liver microsomal preparations suggest that CYP 1A2 is the principal isozyme involved in the initial oxidative metabolism of riluzole and, therefore, potential interactions may occur when riluzole is given concurrently with agents that affect CYP 1A2 activity. Potential inhibitors of CYP 1A2 (e.g., caffeine, phenacetin, theophylline, amitriptyline, and quinolones) could decrease the rate of riluzole elimination, while inducers of CYP 1A2 (e.g., cigarette smoke, charcoal-broiled food, rifampicin, and omeprazole) could increase the rate of riluzole elimination.

Effect of Riluzole On the Metabolism of Other Drugs

CYP 1A2 is the principal isoenzyme involved in the initial oxidative metabolism of riluzole; potential interactions may occur when riluzole is given concurrently with other agents which are also metabolized primarily by CYP 1A2 (e.g., theophylline, caffeine, and tacrine). Currently, it is not known whether riluzole has any potential for enzyme induction in humans.

Drug Laboratory Test Interactions: None known

Read the Rilutek Drug Interactions Center for a complete guide to possible interactions

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 8/4/2009

Side Effects

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