Side Effects of Klonopin (Clonazepam)

Knowing When Its Time to Call Your Doctor or 911

Clonazepam drug molecule


Klonopin (clonazepam) is typically prescribed to treat conditions like panic disorder, anxiety, and certain types of seizures. It is possible to develop a physical dependence to Klonopin if you take the drug for two weeks or more. It is for this reason that drug is prescribed with caution and gradually tapered off once treatment is no longer needed.

If you have been prescribed Klonopin, you should take the time to educate yourself about the possible side effects, withdrawal symptoms, and symptoms of overdose. Rivotril is the Canadian brand name of the drug.


Klonopin is in a class of medications known as benzodiazepines. It comes both in a pill form and as a dissolvable tablet. It has been approved by the Food and Drug Administration to treat certain types of seizure disorders in adults and children and panic disorder with or without agoraphobia (fear of open spaces).

Klonopin can also be used to treat alcohol withdrawal, sleeping difficulties caused by antipsychotic drug use, and anxiety related to bipolar disorder or other mood disorders.

When combined with opioid drugs or alcohol, benzodiazepines can cause serious side effects. Including extreme sedation, difficulty breathing, coma, and even death. To avoid serious complications, you should let your doctor know about any and all over-the-counter, prescription, traditional, naturopathic, nutritional, or homeopathic medications you may be taking.

Side Effects

Some side effects may develop when first stating Klonopin, many of which will resolve on their own as your body begins to adjust to treatment.

According to the Department of Health and Human Services, you should call your doctor if any of these common side effects are severe or fail to go away:

  • Drowsiness
  • Dizziness
  • Unsteadiness
  • Problems with coordination
  • Difficulty thinking or remembering
  • Increased saliva
  • Muscle or joint pain
  • Frequent urination
  • Blurred vision
  • Changes in sex drive or sexual function

Less commonly, Klonopin can cause chest congestion, runny nose, shortness of breath, heart palpitations, hair loss, hirsutism (excessive hair growth) skin rash, coated tongue, constipation, dry mouth, sore gums, lymphadenopathy (swollen lymph nodes), and anemia. 

If you experience these or any other unusual side effects, call your doctor right away.

When to Call 911

In rare cases, side effects can develop rapidly and become potentially life-threatening. Call 911 or seek emergency care if you experience any of the following symptoms:

  • Rash or hives
  • Swelling of the eyes, face, lips, tongue, or throat
  • Difficulty swallowing
  • Shortness of breath and wheezing
  • Hoarseness
  • Disorientation
  • Rapid or irregular heartbeat
  • Nausea or vomiting
  • A feeling of impending doom

These are all symptoms of a severe, all-body allergic reaction known as anaphylaxis. If left untreated, anaphylaxis can lead to respiratory distress, seizure, coma, respiratory or cardiac failure, and death.

Withdrawal Symptoms

You should never suddenly stop taking Klonopin without your doctor's approval if you've been on treatment for more than three months or are using it to control seizures. If you do need to stop, your doctor will gradually wean you off treatment.

Some of the more common withdrawal symptoms include:

  • Irritability
  • Nervousness
  • Trouble sleeping

These symptoms are relatively manageable and will eventually resolve as the daily dosage is decreased.

When to Call Your Doctor

Call your doctor immediately if you experience any of the following, more serious withdrawal symptoms:

  • Abdominal cramps
  • Tingling, burning or prickly sensations
  • Rapid heartbeat
  • Light sensitivity
  • Sound sensitivity
  • Increased sensitivity to touch or pain
  • Profuse sweating
  • Muscle cramps
  • Nausea or vomiting
  • Depression
  • Confusion
  • Paranoia or abnormal thoughts
  • Hallucinations


If you think that someone has overdosed on Klonopin, call 911 or go to your nearest emergency room. You can also call Poison Control at 1-800-222-1222 or go to the Poison Control website for immediate advice and assistance.

Call 911 for Overdose Symptoms

Symptoms of Klonopin overdose include:

  • Clammy skin
  • Extreme sedation
  • Passing out
  • Dilated pupils
  • Impaired coordination
  • Slowed reflexes
  • Trouble breathing
  • Weak and rapid pulse
  • Coma

Treatment may involve gastric lavage (emptying the stomach), intravenous fluids, mechanical ventilation, Romazicon (flumenazil) to reverse the sedative effects, and either Levarterenol (norepinephrine) or Aramine (metaraminol) to treat a dangerous drop in blood pressure.

Disclaimer: This article is not intended to be all-inclusive or replace information provided by your doctor or with the prescription from the manufacturer.

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Article Sources

  • MedlinePlus. Clonazepam. Washington D.C.: U.S. Department of Health and Human Services, National Institutes of Health, U.S. National Library of Medicine; updated September 5, 2018.

  • National Alliance on Mental Illness (NAMI). Clonazepam (Klonopin). Atlanta, Georgia; College of Psychiatric and Neurologic Pharmacists; published October 2016.

  • U.S. Food and Drug Administration. Summary of Prescribing Information: Klonopin Tablets Label. Silver Spring, Maryland; updated October 2017.