Klonopin Side Effects

Generic Name: clonazepam

Note: This document contains side effect information about clonazepam. Some of the dosage forms listed on this page may not apply to the brand name Klonopin.

Some side effects of Klonopin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to clonazepam: oral solution, oral tablet, oral tablet disintegrating

Along with its needed effects, clonazepam (the active ingredient contained in Klonopin) 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:

More common
  • Body aches or pain
  • chills
  • cough
  • difficulty with breathing
  • discouragement
  • dizziness
  • ear congestion
  • feeling sad or empty
  • fever
  • headache
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • loss of voice
  • nasal congestion
  • poor coordination
  • runny nose
  • shakiness and unsteady walk
  • sleepiness or unusual drowsiness
  • sneezing
  • sore throat
  • tiredness
  • trouble with concentrating
  • trouble with sleeping
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual tiredness or weakness
Less common
  • Being forgetful
  • bladder pain
  • bloody or cloudy urine
  • changes in patterns and rhythms of speech
  • diarrhea
  • difficult, burning, or painful urination
  • frequent urge to urinate
  • general feeling of discomfort or illness
  • joint pain
  • loss of appetite
  • lower back or side pain
  • mood or mental changes
  • muscle aches and pains
  • nausea
  • nervousness
  • problems in urination or increase in the amount of urine
  • shivering
  • slurred speech
  • sore throat
  • sweating
  • trouble with speaking
  • vomiting
Rare
  • Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • changes in skin color
  • chest pain or discomfort
  • cold sweats
  • colds
  • confusion
  • cough or hoarseness
  • difficulty with sleeping
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position
  • excessive dreaming
  • excessive muscle tone
  • excitement
  • falling
  • fast, irregular, pounding, or racing heartbeat or pulse
  • feeling mad
  • feeling of unreality
  • flu-like symptoms
  • headache, severe and throbbing
  • lack of feeling or emotion
  • lack or loss of self-control
  • muscle stiffness
  • muscle tension or tightness
  • nightmares
  • pain, inflammation, or swelling in the calves, shoulders, or hands
  • pain or swelling in the arms or legs without any injury
  • pain, tenderness, or swelling of the foot or leg
  • partial or slight paralysis
  • scaling
  • sense of detachment from self or body
  • shakiness in the legs, arms, hands, or feet
  • shortness of breath
  • skin rash
  • sleeplessness
  • swelling around the eyes
  • swelling of the face, ankle, foot, or knees
  • thoughts of killing oneself changes in behavior
  • tightness in the chest
  • trembling or shaking of the hands or feet
  • troubled breathing
  • unable to sleep
  • uncaring
  • vision changes
  • wheezing
Incidence not known
  • Anxiety
  • black, tarry stools
  • bleeding gums
  • blood in the urine or stools
  • change in consciousness
  • chest congestion
  • difficulty with coordination
  • double vision
  • drowsiness
  • dry mouth
  • feeling that others are watching you or controlling your behavior
  • feeling that others can hear your thoughts
  • feeling, seeing, or hearing things that are not there
  • hyperventilation
  • irregular, fast, slow, or shallow breathing
  • irregular, twisting uncontrolled movement of the face, hands, arms, or legs
  • loss of consciousness
  • loss of interest or pleasure
  • loss of memory
  • loss of strength or energy
  • loss of voice
  • muscle weakness
  • pale or blue lips, fingernails, or skin
  • pinpoint red spots on the skin
  • problems with memory
  • restlessness
  • right upper abdominal pain and fullness
  • severe mood or mental changes
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • troubled breathing with exertion
  • uncontrolled eye movements
  • unusual behavior
  • unusual bleeding or bruising
  • unusual weak feeling
  • vivid dreams
  • weight loss or gain

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:

Less common
  • Decreased interest in sexual intercourse
  • difficulty with swallowing
  • dryness or soreness of the throat
  • heavy bleeding
  • hives
  • inability to have or keep an erection
  • longer than usual time to ejaculation of semen
  • loss in sexual ability, desire, drive, or performance
  • pain or tenderness around the eyes and cheekbones
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • voice changes
Rare
  • Acid or sour stomach
  • ankle, knee, or great toe joint pain
  • belching
  • bleeding after defecation
  • blistering, burning, crusting, dryness, or flaking of the skin
  • bloated
  • blurred or loss of vision
  • decrease or change in vision
  • difficulty with moving
  • disturbed color perception
  • double vision
  • dryness of the eyes
  • earache
  • excess air or gas in stomach or intestines
  • feeling of constant movement of self or surroundings
  • feeling of warmth
  • frequent bowel movements
  • full feeling
  • hair loss or thinning of the hair
  • halos around lights
  • heartburn
  • increased watering of the mouth
  • indigestion
  • irregularities in menstruation
  • itching in genital or other skin areas
  • itching, scaling, severe redness, soreness, or swelling of the skin
  • joint stiffness or swelling
  • leg or muscle cramps
  • loss of taste
  • night blindness
  • nosebleeds
  • overbright appearance of lights
  • pain in the breasts or pelvic area
  • pain in the leg, nape, or back
  • passing gas
  • red, sore eyes
  • redness of the face, neck, arms, and occasionally, upper chest
  • redness or swelling in the ear
  • sensation of spinning
  • skin rash cracks in the skin at the corners of the mouth
  • smaller amount of semen ejaculated than usual
  • sore on the edge of the eyelid
  • soreness or redness around the fingernails and toenails
  • stomach discomfort, upset, or pain
  • thickening of the tongue
  • thirst
  • tooth disorder
  • toothache
  • tunnel vision
  • twitching of the eyes
  • uncomfortable swelling around the anus
  • worsening of acne
Incidence not known
  • Burning feeling in the chest or stomach
  • difficulty having a bowel movement (stool)
  • increased appetite
  • increased hair growth, especially on the face
  • increased in sexual ability, desire, drive, or performance
  • increased interest in sexual intercourse
  • sore gums
  • tenderness in the stomach area

For Healthcare Professionals

Applies to clonazepam: oral tablet, oral tablet disintegrating

Nervous system

Nervous system side effects are common, particularly at the initiation of therapy and include drowsiness, fatigue, ataxia, confusion, depression, daytime anxiety, and amnesia. Nystagmus, diplopia, vertigo, headache, respiratory depression, tremor and slurred speech have also been reported less frequently.

Sedation may initially occur in up to 50% of treated patients. Ataxia may occur in 30% of patients. Five to 6% of patients treated with clonazepam for seizures may develop more frequent seizures or a new type of seizure disorder. Weakness and hypotonia have also been reported. A case report has suggested that clonazepam may induce Tourette's syndrome.

Psychiatric

Behavioral problems have been reported in as many as 30% of treated patients.

Psychiatric side effects have been reported and include behavioral disinhibition (particularly sexual disinhibition), depression, and rarely, psychosis and mania.

Other

Other side effects have included withdrawal symptoms (similar to those which may occur after withdrawal of barbiturates and alcohol) which have been reported after abrupt cessation of clonazepam (the active ingredient contained in Klonopin) Specifically, seizures, agitation, restlessness, anxiety, delirium, psychosis, dysphoria, insomnia, tremor, abdominal cramps, vomiting, rash, and sweating have been reported to have occurred, especially after long-term therapy.

Genitourinary

In one study, anorgasmia occurred in 44% of patients treated with clonazepam (the active ingredient contained in Klonopin) while anorgasmia occurred in only 6% of patients treated with placebo.

Genitourinary side effects may include urinary incontinence, anorgasmia, ejaculatory delay, and erectile dysfunction.

Hematologic

Hematologic side effects including thrombocytopenia have been reported rarely.

Gastrointestinal

Gastrointestinal side effects including hypersalivation, diarrhea, constipation, nausea, increased appetite, and anorexia have been reported.

Respiratory

Respiratory side effects including bronchial hypersecretion have been reported.

Dermatologic

Dermatologic side effects have included cases of rashes associated with clonazepam (the active ingredient contained in Klonopin) therapy. A case of erythema multiforme associated with clonazepam therapy has also been reported.

Ocular

Clonazepam (the active ingredient contained in Klonopin) is contraindicated in patients with narrow angle glaucoma.

Ocular side effects including acute worsening of narrow angle glaucoma is possible with clonazepam therapy.

Metabolic

Metabolic side effects have included exacerbation of seizure disorders in some patients with acute intermittent porphyria. However, a case report has suggested that clonazepam (the active ingredient contained in Klonopin) may be beneficial in this setting as well.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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