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 enough of the the drug over time. 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 another brand name of clonazepam used in some other countries.


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, 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

When combined with opioid drugs or alcohol, benzodiazepines can cause serious 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.

You should call your doctor if any of these common side effects are severe or fail to go away:

  • Changes in sex drive or sexual function
  • Difficulty thinking or remembering
  • Dizziness
  • Drowsiness
  • Problems with coordination
  • Unsteadiness
  • Vision changes

Rarely, Klonopin can cause the following side effects:

  • Anemia
  • Chest congestion
  • Coated tongue
  • Constipation
  • Dry mouth
  • Hair loss
  • Heart palpitations
  • Hirsutism (excessive hair growth)
  • Lymphadenopathy (swollen lymph nodes)
  • Runny nose
  • Shortness of breath
  • Skin rash
  • Sore gums

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

This can potentially be 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, particularly if you've been on treatment for some time or are using it to control seizures. If you do need to stop, your doctor will generally 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. Sometimes withdrawal symptoms can last for a long time or longer than expected, however.

When to Call Your Doctor

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

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


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

Treatment may involve gastric lavage (emptying the stomach), intravenous fluids, mechanical ventilation, Romazicon (flumenazil) to reverse the sedative effects, and medications such as Levarterenol (norepinephrine) to treat a dangerous drop in blood pressure if present.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

3 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Klonopin.

  2. Food and Drug Administration. FDA warns about serious risks and death when combining opioid pain or cough medicines with benzodiazepines; requires its strongest warning.

  3. Wang SM, Kim JB, Sakong JK, et al. The Efficacy and Safety of Clonazepam in Patients with Anxiety Disorder Taking Newer Antidepressants: A Multicenter Naturalistic Study. Clin Psychopharmacol Neurosci. 2016;14(2):177-83. doi: 10.9758%2Fcpn.2016.14.2.177. doi:10.9758%2Fcpn.2016.14.2.177

Additional Reading

By Marcia Purse
Marcia Purse is a mental health writer and bipolar disorder advocate who brings strong research skills and personal experiences to her writing.