Clonazepam Side Effects

Medically reviewed by Drugs.com. Last updated on Oct 30, 2024.

Applies to clonazepam: oral tablet, oral tablet disintegrating.

Precautions

It is very important that your doctor check your progress at regular visits to see if the medicine is working properly and to allow for changes in the dose. Blood tests may be needed to check for unwanted effects.

Tell your doctor if you are pregnant or planning to become pregnant. Using this medicine during the later pregnancy may cause problems in your newborn baby (eg, sedation or withdrawal symptoms). Tell your doctor right away if your baby has an abnormal sleep pattern, diarrhea, feeding problems, a high-pitched cry, irritability, low muscle tone, restlessness, shakiness or tremors, sluggishness, trouble breathing, weight loss, vomiting, or fails to gain weight. If you think you have become pregnant while using the medicine, tell your doctor right away.

This medicine may be habit-forming. If you feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions.

This medicine may cause drowsiness, trouble with thinking, trouble with controlling movements, or trouble with seeing clearly. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert or able to think or see well.

If you develop any unusual and strange thoughts or behavior while you are taking clonazepam, be sure to discuss it with your doctor. Some changes that have occurred in people taking this medicine are like those seen in people who drink alcohol and then act in a manner that is not normal. Other changes may be more unusual and extreme, such as confusion, worsening of depression, hallucinations (seeing, hearing, or feeling things that are not there), suicidal thoughts, and unusual excitement, nervousness, or irritability.

If you have been taking this medicine for a long time, do not stop taking it without checking first with your doctor. Your doctor may want you to gradually reduce the amount you are using before stopping it completely. This may help prevent worsening of your condition and reduce the possibility of withdrawal symptoms, including actions that are out of control, anxiety, blurred vision, decreased awareness or responsiveness, discouragement, dizziness, environment seems unreal, feeling of unreality, feeling sad or empty, irritability, lack of appetite, loss of interest or pleasure, mimicry of speech or movements, mutism, negativism, nervousness, peculiar postures or movements, mannerisms or grimacing, seeing, hearing, or feeling things that are not there, sense of detachment from self or body, seizures, severe sleepiness, talking, feeling, and acting with excitement, trouble concentrating and sleeping.

Symptoms of an overdose include: change in consciousness, changes in patterns and rhythms of speech, hallucinations, lack of coordination, loss of consciousness, loss of strength or energy, mood or mental changes, muscle pain or weakness, nightmares, sleepiness or unusual drowsiness, shakiness and unsteady walk, slurred speech, trouble in speaking, trouble sleeping, unsteadiness, trembling, or other problems with muscle control or coordination, unusual drowsiness, dullness, tiredness, weakness or feeling of sluggishness, unusual excitement, nervousness, restlessness, or irritability, or unusual weak feeling. Call your doctor right away if you notice these symptoms.

This medicine will add to the effects of alcohol and other central nervous system (CNS) depressants. CNS depressants are medicines that slow down the nervous system, which may cause drowsiness or make you less alert. Some examples of CNS depressants are antihistamines or medicine for hay fever, allergies or colds, sedatives, tranquilizers, or sleeping medicine, prescription pain medicine or narcotics, barbiturates or seizure medicines, muscle relaxants, or anesthetics (numbing medicines), including some dental anesthetics. Check with your doctor before taking any of these products while you are using this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of clonazepam

Along with its needed effects, clonazepam 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 clonazepam:

Get emergency help immediately if any of the following symptoms of overdose occur while taking clonazepam:

Symptoms of overdose

• agitation
• change in consciousness
• changes in patterns and rhythms of speech
• confusion
• loss of consciousness
• loss of strength or energy
• mood or mental changes
• nightmares
• shakiness and unsteady walk
• sleepiness or unusual drowsiness
• slurred speech
• talkativeness
• trouble speaking
• unsteadiness, trembling, or other problems with muscle control or coordination
• unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
• unusual excitement, nervousness, restlessness, or irritability
• unusual weak feeling

Other side effects of clonazepam

Some side effects of clonazepam 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:

For healthcare professionals

Applies to clonazepam: oral tablet, oral tablet disintegrating.

General adverse events

The most commonly reported side effects included drowsiness, somnolence, ataxia, and behavior problems.^[Ref]

Nervous system

• 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]

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]

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

• 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]

Transient fatigue, lassitude, slowed reaction, and/or tiredness may occur, and usually disappear spontaneously when treatment is continued or upon dose reductions.^[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

• 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]

Tachycardia occurred after IV administration.^[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]

See also:

Frequently asked questions

• Is clonazepam a controlled substance?

Further information

Clonazepam side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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