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Flexeril (Cyclobenzaprine Hydrochloride) - Side Effects and Adverse Reactions

 
 



ADVERSE REACTIONS

Incidence of most common adverse reactions in the 2 double-blind [ Note: FLEXERIL 10 mg data are from one clinical trial. FLEXERIL 5 mg and placebo data are from two studies. ] , placebo-controlled 5 mg studies (incidence of > 3% on FLEXERIL 5 mg):

FLEXERIL 5 mg
N=464
FLEXERIL 10 mg
N=249
Placebo
N=469
Drowsiness29%38%10%
Dry Mouth21%32%7%
Fatigue6%6%3%
Headache5%5%8%

Adverse reactions which were reported in 1% to 3% of the patients were: abdominal pain, acid regurgitation, constipation, diarrhea, dizziness, nausea, irritability, mental acuity decreased, nervousness, upper respiratory infection, and pharyngitis.

The following list of adverse reactions is based on the experience in 473 patients treated with FLEXERIL 10 mg in additional controlled clinical studies, 7607 patients in the postmarketing surveillance program, and reports received since the drug was marketed. The overall incidence of adverse reactions among patients in the surveillance program was less than the incidence in the controlled clinical studies.

The adverse reactions reported most frequently with FLEXERIL were drowsiness, dry mouth and dizziness. The incidence of these common adverse reactions was lower in the surveillance program than in the controlled clinical studies:

Clinical Studies With
FLEXERIL 10 mg
Surveillance Program
With FLEXERIL 10 mg
Drowsiness39%16%
Dry Mouth27%7%
Dizziness11%3%

Among the less frequent adverse reactions, there was no appreciable difference in incidence in controlled clinical studies or in the surveillance program. Adverse reactions which were reported in 1% to 3% of the patients were: fatigue/tiredness, asthenia, nausea, constipation, dyspepsia, unpleasant taste, blurred vision, headache, nervousness, and confusion.

The following adverse reactions have been reported in post-marketing experience or with an incidence of less than 1% of patients in clinical trials with the 10 mg tablet:

      Body as a Whole:   Syncope; malaise.

      Cardiovascular:   Tachycardia; arrhythmia; vasodilatation; palpitation; hypotension.

      Digestive:   Vomiting; anorexia; diarrhea; gastrointestinal pain; gastritis; thirst; flatulence; edema of the tongue; abnormal liver function and rare reports of hepatitis, jaundice and cholestasis.

      Hypersensitivity:   Anaphylaxis; angioedema; pruritus; facial edema; urticaria; rash.

      Musculoskeletal:   Local weakness.

      Nervous System and Psychiatric:   Seizures, ataxia; vertigo; dysarthria; tremors; hypertonia; convulsions; muscle twitching; disorientation; insomnia; depressed mood; abnormal sensations; anxiety; agitation; psychosis, abnormal thinking and dreaming; hallucinations; excitement; paresthesia; diplopia.

      Skin:   Sweating.

      Special Senses:   Ageusia; tinnitus.

      Urogenital:   Urinary frequency and/or retention.

Causal Relationship Unknown

Other reactions, reported rarely for FLEXERIL under circumstances where a causal relationship could not be established or reported for other tricyclic drugs, are listed to serve as alerting information to physicians:

      Body as a whole:   Chest pain; edema.

      Cardiovascular:   Hypertension; myocardial infarction; heart block; stroke.

      Digestive:   Paralytic ileus, tongue discoloration; stomatitis; parotid swelling.

      Endocrine:   Inappropriate ADH syndrome.

      Hematic and Lymphatic:   Purpura; bone marrow depression; leukopenia; eosinophilia; thrombocytopenia.

      Metabolic, Nutritional and Immune:   Elevation and lowering of blood sugar levels; weight gain or loss.

      Musculoskeletal:   Myalgia.

      Nervous System and Psychiatric:   Decreased or increased libido; abnormal gait; delusions; aggressive behavior; paranoia; peripheral neuropathy; Bell's palsy; alteration in EEG patterns; extrapyramidal symptoms.

      Respiratory:   Dyspnea.

      Skin:   Photosensitization; alopecia.

      Urogenital:   Impaired urination; dilatation of urinary tract; impotence; testicular swelling; gynecomastia; breast enlargement; galactorrhea.



REPORTS OF SUSPECTED FLEXERIL SIDE EFFECTS / ADVERSE REACTIONS

Below is a sample of reports where side effects / adverse reactions may be related to Flexeril. The information is not vetted and should not be considered as verified clinical evidence.

Possible Flexeril side effects / adverse reactions in 57 year old female

Reported by a pharmacist from United States on 2011-11-07

Patient: 57 year old female

Reactions: Confusional State

Suspect drug(s):
Actonel
    Dosage: unk

Bystolic
    Dosage: unk

Flexeril
    Dosage: unk

Imdur
    Dosage: unk

Klor-CON
    Dosage: unk

Lasix
    Dosage: unk

Lipitor
    Dosage: 40 mg, unk

Nexium
    Dosage: unk

Paxil
    Dosage: unk

Vivelle
    Dosage: unk

Xanax
    Dosage: unk



Possible Flexeril side effects / adverse reactions in 46 year old female

Reported by a consumer/non-health professional from United States on 2011-11-23

Patient: 46 year old female weighing 110.2 kg (242.5 pounds)

Reactions: Suicidal Ideation, Crying

Suspect drug(s):
Flexeril



Possible Flexeril side effects / adverse reactions in 55 year old female

Reported by a physician from United States on 2012-01-25

Patient: 55 year old female weighing 66.0 kg (145.2 pounds)

Reactions: Product Compounding Quality Issue, Reaction TO Drug Excipients

Suspect drug(s):
Flexeril
    Indication: Fibromyalgia

Salagen
    Indication: Sjogren's Syndrome
    Start date: 2011-09-01

Other drugs received by patient: Mobic; Vivelle-DOT



See index of all Flexeril side effect reports >>

Drug label data at the top of this Page last updated: 2006-11-30

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