Side Effects of Flexeril (cyclobenzaprine)

Flexeril (cyclobenzaprine) is a muscle relaxant used for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions, in combination with rest and physical therapy.

Flexeril relieves muscle spasms in the muscle itself, rather than in the nerves controlling the muscles. It does not affect muscle function and works through a complex mechanism within the nervous system, likely in the brainstem.

Common side effects of Flexeril include drowsiness, dry mouth, fatigue, headaches, and dizziness.

Other reported side effects of Flexeril include nausea, constipation, blurred vision, unpleasant taste, nervousness, confusion, acid reflux, and abdominal pain or discomfort.

Serious side effects of Flexeril include seizures, abnormal heartbeats, stroke, heart attacks, and heatstroke.

Abrupt cessation of Flexeril after prolonged therapy may cause withdrawal symptoms such as headaches, nausea, and weakness.

Drug interactions of Flexeril include tricyclic antidepressants because Flexeril is chemically related to this class of drugs.

Flexeril should not be taken with or within two weeks of any monoamine oxidase inhibitors (MAOs) such as isocarboxazid, phenelzine, tranylcypromine, and procarbazine, as it can lead to high fever, convulsions, and even death.

Flexeril interacts with other medications and drugs that slow the brain’s processes, such as alcohol, barbiturates, benzodiazepines, and narcotics.

There are no adequate studies of Flexeril in pregnant women. It can be used during pregnancy if necessary, but caution is advised. It is unknown if Flexeril is secreted in breast milk, so caution is also advised when using it in breastfeeding women.

What are the side effects of Flexeril?

What are the common side effects of Flexeril?

The most common side effects of Cyclobenzaprine include:

Other reported side effects include:

• Nausea
• Constipation
• Blurred vision
• Unpleasant taste
• Nervousness
• Confusion
• Acid reflux
• Abdominal pain or discomfort

What are the serious side effects of Flexeril?

Possible serious side effects include:

Abrupt cessation after prolonged therapy may cause withdrawal symptoms such as headaches, nausea, and weakness.

Is Flexeril addictive?

Drug Abuse And Dependence

• Frequent administration of Flexeril may rarely produce nausea, headache, and malaise upon abrupt cessation. These symptoms are not indicative of addiction.

What drugs interact with Flexeril?

• Flexeril may have life-threatening interactions with MAO inhibitors.
• Flexeril may enhance the effects of alcohol, barbiturates, and other CNS depressants.
• Tricyclic antidepressants may block the antihypertensive action of guanethidine and similar compounds.
• Tricyclic antidepressants may increase the seizure risk in patients taking tramadol.

Flexeril side effects list for healthcare professionals

The most common adverse reactions in double-blind placebo-controlled studies of 5 mg Flexeril:

Adverse reactions reported in 1% to 3% of patients include:

• Abdominal pain
• Acid regurgitation
• Constipation
• Diarrhea
• Dizziness
• Nausea
• Irritability
• Decreased mental acuity
• Nervousness
• Upper respiratory infection
• Pharyngitis

Other adverse reactions reported with Flexeril include drowsiness, dry mouth, and dizziness.

Less frequent adverse reactions include:

• Fatigue/tiredness
• Asthenia
• Nausea
• Constipation
• Dyspepsia
• Unpleasant taste
• Blurred vision
• Headache
• Nervousness
• Confusion

Rare adverse reactions reported with Flexeril include:

• Chest pain
• Edema
• Hypertension
• Myocardial infarction
• Heart block
• Stroke
• Paralytic ileus
• Tongue discoloration
• Stomatitis
• Parotid swelling
• Inappropriate ADH syndrome
• Purpura
• Bone marrow depression
• Weight gain or loss
• Myalgia
• Peripheral neuropathy
• Seizures
• Ataxia
• Vertigo
• Dysarthria
• Tremors
• Hypotonia
• Convulsions
• Muscle twitching
• Disorientation
• Insomnia
• Depressed mood
• Abnormal sensations
• Anxiety
• Agitation
• Psychosis
• Hallucinations
• Paresthesia
• Diplopia
• Sweating
• Ageusia
• Tinnitus
• Urinary frequency and/or retention
• Syncope
• Malaise
• Tachycardia
• Arrhythmia
• Vasodilatation
• Palpitation
• Decreased libido
• Abnormal gait
• Delusions
• Aggressive behavior
• Peripheral neuropathy
• Bell’s palsy
• Altered EEG patterns
• Hypertonia
• Convulsions
• Muscle twitching
• Disorientation
• Insomnia
• Depressed mood
• Abnormal sensations
• Anxiety
• Agitation
• Psychosis
• Abnormal thinking
• Hallucinations
• Excitement
• Paresthesia
• Diplopia
• Sweating
• Ageusia
• Tinnitus
• Urinary frequency and/or retention
• Chest pain
• Edema
• Hypertension
• Myocardial infarction
• Heart block
• Stroke
• Paralytic ileus
• Tongue discoloration
• Stomatitis
• Parotid swelling
• Inappropriate ADH syndrome
• Purpura
• Bone marrow depression
• Weight gain or loss
• Myalgia
• Peripheral neuropathy
• Seizures
• Ataxia
• Vertigo
• Dysarthria
• Tremors
• Hypotonia
• Convulsions
• Muscle twitching
• Disorientation
• Insomnia
• Depressed mood
• Abnormal sensations
• Anxiety
• Agitation
• Psychosis
• Abnormal thinking
• Hallucinations
• Excitement
• Paresthesia
• Diplopia
• Sweating
• Ageusia
• Tinnitus
• Urinary frequency and/or retention

Causal Relationship Unknown

Other reactions reported rarely for Flexeril and other tricyclic drugs are listed as alerting information to physicians:

• Chest pain
• Edema
• Hypertension
• Myocardial infarction
• Heart block
• Stroke
• Paralytic ileus
• Tongue discoloration
• Stomatitis
• Parotid swelling
• Inappropriate ADH syndrome
• Purpura
• Bone marrow depression
• Weight gain or loss
• Myalgia
• Peripheral neuropathy
• Seizures
• Ataxia
• Vertigo
• Dysarthria
• Tremors
• Hypotonia
• Convulsions
• Muscle twitching
• Disorientation
• Insomnia
• Depressed mood
• Abnormal sensations
• Anxiety
• Agitation
• Psychosis
• Hallucinations
• Paresthesia
• Diplopia
• Sweating
• Ageusia
• Tinnitus
• Urinary frequency and/or retention

Summary

Flexeril (cyclobenzaprine) is a muscle relaxant used for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions. Common side effects of Flexeril include drowsiness, dry mouth, fatigue, headaches, and dizziness. Other reported side effects of Flexeril include nausea, constipation, blurred vision, unpleasant taste, nervousness, confusion, acid reflux, and abdominal pain or discomfort. Caution is advised when using Flexeril in pregnant or breastfeeding women.