Note: This document contains side effect information about clonazepam. Some dosage forms listed on this page may not apply to the brand name Klonopin.
Summary
Common side effects of Klonopin include: drowsiness. Other side effects include: upper respiratory tract infection, ataxia, depression, and dizziness. Continue reading for a comprehensive list of adverse effects.
Applies to clonazepam: oral conventional or orally disintegrating tablets.
Warning
-
Concomitant Use with Opiates
- Concomitant use of benzodiazepines and opiates may result in profound sedation, respiratory depression, coma, and death.700 701 703 705 706 707
- Reserve concomitant use for patients in whom alternative treatment options are inadequate; use lowest effective dosages and shortest possible duration of concomitant therapy and monitor closely for respiratory depression and sedation.700 703 (See Specific Drugs under Interactions.)
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Potential for Abuse, Addiction, and Other Serious Risks
- A boxed warning has been included in the prescribing information for all benzodiazepines describing risks of abuse, misuse, addiction, physical dependence, and withdrawal reactions.900
- Abuse and misuse can result in overdose or death, especially when benzodiazepines are combined with other medicines, such as opioid pain relievers, alcohol, or illicit drugs.900
- Assess a patient’s risk of abuse, misuse, and addiction.900 Standardized screening tools are available ([Web]).900
- To reduce risk of acute withdrawal reactions, use a gradual dose taper when reducing dosage or discontinuing benzodiazepines.900 Take precautions when benzodiazepines are used in combination with opioid medications.900
Side effects include:
Sedation/drowsiness, ataxia/hypotonia, behavioral disturbances (principally in children) including aggressiveness, irritability, agitation, hyperkinesis.
For Healthcare Professionals
Applies to clonazepam: oral tablet, oral tablet disintegrating.
General
The most commonly reported side effects included drowsiness, somnolence, ataxia, and behavior problems.[Ref]
Nervous system
Reversible ataxia, dysarthria, anterograde amnesia, and nystagmus may occur, especially in long-term treatment and/or at high doses.
Transient somnolence, dizziness, ataxia, lightheadedness, muscular hypotonia, and/or coordination disturbances may occur, and usually disappear spontaneously when treatment is continued or upon dose reductions.[Ref]
Very common (10% or more): Drowsiness (up to 50%), somnolence (up to 50%), ataxia (up to 30%), dizziness (up to 12%)
Common (1% to 10%): Abnormal coordination, dysarthria, intellectual ability reduced, memory disturbance, nystagmus
Rare (0.01% to 0.1%): Convulsions, headache
Very rare (less than 0.01%): Generalized fits, lightheadedness
Frequency not reported: Activation of new types of seizures, amnestic effects, anterograde amnesia/amnesia, aphonia, attention lack, coma, coordination disturbances, decreased movement and gait coordination, disturbance in attention, dysdiadochokinesis/inability to perform rapid, alternating movements, dysphagia, epileptic seizures, extremity numbness and tingling, forgetfulness, head fullness, hemiparesis, hyperactivity, hyperphagia, hypersensitivity to light/noise/physical contact, hypertonia, hypoesthesia, impaired concentration/poor concentration, lethargy, migraine, motion sickness, muscular hypotonia, paresis, paresthesia, seizures, speech slowing/slurring, taste loss, tremor, vertigo, visual field defect
Postmarketing reports: Choreiform movements, hypotonia, preexisting brain damage[Ref]
Psychiatric
Very common (10% or more): Behavior problems (up to 25%)
Common (1% to 10%): Confusion/confusional state, decreased libido, depression, emotional lability, nervousness
Rare (0.01% to 0.1%): Decrease in sexual drive, loss of libido
Frequency not reported: Aggressive behavior/aggressive reaction/aggression/aggressiveness, agitation, anger, anxiety, apathy, depersonalization, derealization, disorientation, drug withdrawal symptoms, dysphoria, excessive dreaming, excitability/excitement, extreme anxiety, feeling mad, hallucinations, hostility, hysteria, illusion, inappropriate behavior, increased libido, insomnia, irritability, nightmares, organic disinhibition, physical dependence, psychological dependence, psychosis, psychotic disorders, restlessness, sleep disorder, sleep disturbance, suicidal attempt, suicide ideation, tension, vivid dreams, worsening/emergence of clinical depression
Postmarketing reports: Abnormal dreams, change in libido, dependence, encopresis[Ref]
Reversible inappropriate behavior may occur, especially in long-term treatment and/or at high doses.[Ref]
Respiratory
Very common (10% or more): Upper respiratory tract infection (up to 10%)
Common (1% to 10%): Bronchitis, coughing, pharyngitis, rhinitis, sinusitis
Rare (0.01% to 0.1%): Respiratory depression
Frequency not reported: Asthmatic attach, bronchial hypersecretion/hypersecretion in upper respiratory passages, chest congestion, dyspnea, excessive sneezing, hoarseness, mucus obstruction of the nasopharynx, nosebleed, pneumonia, rhinorrhea, shortness of breath, yawning
Postmarketing reports: Airway obstruction, pharyngeal edema[Ref]
Genitourinary
Common (1% to 10%): Colpitis, dysmenorrhea, ejaculation delayed, impotence, micturition frequency, urinary tract infection
Rare (0.01% to 0.1%): Erectile dysfunction, urinary incontinence
Frequency not reported: Bladder dysfunction, breast pain, dysuria, ejaculation decreased, enuresis/feeling of enuresis, menstrual irregularity, nocturia, pain pelvic, polyuria, urinary retention, urinary tract bleeding, urine discoloration[Ref]
Other
Transient fatigue, lassitude, slowed reaction, and/or tiredness may occur, and usually disappear spontaneously when treatment is continued or upon dose reductions.[Ref]
Common (1% to 10%): Fatigue, lassitude, tiredness
Frequency not reported: Accident, drunkenness, earache, fever, herpes simplex infection, hyperacusis, injury, malaise, otitis, pain, paradoxical reaction, reaction slowed/decreased, shivering, thirst, wound
Postmarketing reports: Falls, general deterioration[Ref]
Gastrointestinal
Common (1% to 10%): Abdominal pain, constipation
Rare (0.01% to 0.1%): Epigastric discomfort/symptoms, gastrointestinal symptoms, nausea
Frequency not reported: Abdominal discomfort, bowel movements frequent, coated tongue, dyspepsia, flatulence, gastrointestinal inflammation, hemorrhoids, pyrosis, salivary hypersecretion/saliva increased/hypersalivation, stomach upset, tongue thick, toothache, tooth disorder, vomiting
Postmarketing reports: Diarrhea, dry mouth, gastritis, sore gums[Ref]
Musculoskeletal
Common (1% to 10%): Muscle weakness, myalgia
Frequency not reported: Ankle pain, arthralgia, back pain, foot pain, fracture traumatic, knee pain, knee swelling, jaw pain, leg cramps, leg pain, lumbago, muscle cramps, muscle pain, nape pain, shoulder pain, sprains, strains, tendinitis, twitching
Postmarketing reports: Fractures[Ref]
Hypersensitivity
Common (1% to 10%): Allergic reaction
Rare (0.01% to 0.1%): Angioedema
Frequency not reported: Anaphylaxis[Ref]
Ocular
Common (1% to 10%): Blurred vision
Frequency not reported: Diplopia/double vision, eye irritation, eye twitching, periorbital edema, stye, visual disturbance, xerophthalmia
Postmarketing reports: Abnormal eye movements, "glassy-eyed" appearance[Ref]
Reversible vision disorders (e.g., diplopia) may occur, especially in long-term treatment and/or at high doses.[Ref]
Metabolic
Common (1% to 10%): Appetite decreased
Frequency not reported: Anorexia, dehydration, gout, hunger abnormal, increased appetite, weight gain, weight loss[Ref]
Immunologic
Common (1% to 10%): Influenza
Frequency not reported: Infection mycotic, infection streptococcal, infection viral, moniliasis[Ref]
Dermatologic
Rare (0.01% to 0.1%): Pigmentation changes, pruritus, rash/skin rash, transient hair loss, urticaria
Frequency not reported: Abrasions, acne flare, alopecia/transient hair loss, bleeding dermal, burning skin, cellulitis, dermatitis contact, facial edema, hair loss, hirsutism, pustular reaction, skin disorder, sweating, xeroderma
Postmarketing reports: Angioneurotic edema, pigmentation disorder[Ref]
Hematologic
Rare (0.01% to 0.1%): Decreased platelet count
Frequency not reported: Anemia, blood dyscrasias, eosinophilia, infectious mononucleosis, leukopenia, lymphadenopathy
Postmarketing reports: Thrombocytopenia[Ref]
Cardiovascular
Tachycardia occurred after IV administration.[Ref]
Frequency not reported: Ankle edema, chest pain, edema, flushing, foot edema, palpitations, postural hypotension, tachycardia, thrombophlebitis leg
Postmarketing reports: Cardiac arrest, cardiac failure, thrombophlebitis, thrombosis[Ref]
Hepatic
Frequency not reported: Abnormal liver function tests, hepatomegaly
Postmarketing reports: Transient elevations of serum transaminases and alkaline phosphatase[Ref]
Endocrine
Frequency not reported: Incomplete precocious puberty/premature secondary sex characteristics[Ref]
Local
Frequency not reported: Localized inflammation[Ref]
Renal
Frequency not reported: Cystitis[Ref]
