What Are Benzodiazepines?

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Benzodiazepines (BZDs) are central nervous system depressants, or tranquilizers. They slow down brain activity, relax muscles, calm jittery nerves, and induce sleepiness. Short-term use of benzodiazepines can treat anxiety, insomnia, panic disorder, social phobias, and seizures.

However, long-term use can lead to prescription drug addiction or misuse. Combining BZDs with other substances, such as alcohol or opioids, is dangerous. All benzodiazepines come with black box warnings (the Food and Drug Administration's strictest drug warning) to improve safe use.

This article describes the different types of benzodiazepines, how they work, their uses, side effects, and more.

pharmacist showing patient medications benzodiazepines

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Benzodiazepines are primarily used as sedatives to relieve anxiety, stop panic attacks, and help people sleep. However, BZDs have a wide range of uses. They can be prescribed to treat:

How Do Benzodiazepines Work?

Benzodiazepines are central nervous system (CNS) depressants. They work by binding with inhibitory gamma-aminobutyric acid (GABA) neurotransmitter receptors in the brain and throughout the central nervous system to block messages of fear, anxiety, and distress.

In doing so, they calm nerves, reduce anxiety, relax muscles, and cause drowsiness.

Benzodiazepine Types

There are many different types of benzodiazepines. The most commonly prescribed BZDs are:

  • Valium (diazepam)
  • Xanax (alprazolam)
  • Klonopin (clonazepam)
  • Ativan (lorazepam)
  • Restoril (temazepam)

Benzodiazepines are typically prescribed as tablets or capsules. Occasionally, they are administered as injectables or suppositories.

All BZDs are categorized as Schedule IV controlled substances and come with the FDA's strictest black box warning.

Black Box Warnings

The FDA requires pharmaceutical companies to add a "black box warning" (text written inside a black box) to all benzodiazepine prescriptions. The word "WARNINGS" is written in all caps to alert people of dangerous or life-threatening risks.

Different benzodiazepine types have different "onset of action" times, which affect how long it takes for them to start taking effect and how long they stay in your body.

Benzodiazepines are classified based on what's called their elimination half-life, which means:

  • Short-acting BZDs have an average half-life elimination rate ranging from one to 12 hours.
  • Long-acting BZDs have a half-life ranging between 40 and 250 hours.

It takes about five half-lives to eliminate a drug from the body.

Some BZDs have a fast onset of action and kick in within a few minutes. Others have a slower onset of action and don't reach peak levels for over an hour.

Faster-acting benzodiazepines with a shorter half-life are generally considered more addictive. They have a greater risk of dependence and a higher rate of misuse.

Commonly Prescribed Benzodiazepines: Onset of Action & Elimination Half-Life
Trade Name (Generic Name)  Onset of Action  Half-Life
Ativan (lorazepam) 15–30 minutes 10–20 hours
Dalmane (flurazepam) 30–60 minutes 47–100 hours
Halcion (triazolam) 20–40 minutes 2–6 hours
Klonopin (clonazepam) 20–60 minutes 20–60 hours
Librium (chlordiazepoxide) 1–4 hours 6–30 hours
Onfi (clobazam) 0.5–4 hours 36–42 hours
ProSom (estazolam) 0.5–4 hours 8–24 hours
Restoril (temazepam) 20–90 minutes 8–20 hours
Serax (oxazepam) 2–4 hours 5–15 hours
Tranxene (clorazepate) 0.5–2 hours 48–179 hours
Valium (diazepam) 1–5 minutes 20–100 hours
Xanax (alprazolam) 20–60 minutes 11–16 hours

Side Effects and Risks

The most common side effects of benzodiazepines are:

  • Drowsiness
  • Decreased alertness
  • Lethargy
  • Fatigue

Low libido (sex drive) and erectile dysfunction (ED) are also side effects. A 2013 study found that men taking benzodiazepines were two to three times more likely to have ED.

At higher dosages or with prolonged use, benzodiazepines can also lead to the following side effects:

  • Aggressive behavior
  • Blurred vision
  • Confusion or disorientation
  • Dizziness
  • Impaired motor coordination
  • Irritability
  • Mood swings
  • Slurred speech
  • Vertigo (spinning sensation)

Because these drugs slow reaction times, they can also increase the risk of having an accident when driving a motor vehicle or operating heavy machinery.

Benzodiazepines and Pregnancy

Benzodiazepines increase the risk of miscarriage during early pregnancy. Although insomnia and anxiety are common during pregnancy, a 2019 study found that using any type of BZD (short- or long-acting) to treat these conditions during early pregnancy increased the risk of spontaneous abortion.

Drug Interactions

Benzodiazepines exaggerate the effects of alcohol and other medications. Although it's possible to overdose on Valium, Xanax, or other BZDs when used alone, substances such as alcohol and opioids cause drug interactions that significantly increase overdose risk when combined with BZDs.

Flumazenil counteracts the sedative effect of benzodiazepines. It's FDA-approved as a benzodiazepine antagonist and can be a lifesaving treatment during an overdose.

Poison Control

Contact Poison Control right away if you or someone you know is having a toxic drug interaction. You can get help online or call 1-800-222-1222. Call 911 immediately if the person has a seizure, collapses, or is having trouble breathing.


Benzodiazepine misuse is an ongoing public health concern.

When Valium was first introduced in 1963, healthcare providers thought it was less likely to cause dependence than previous sedatives. It wasn't until many years later that providers and the FDA discovered that long-term use of benzodiazepines often leads to dependence and misuse.

A 2019 study of benzodiazepines being taken as prescribed vs. misused found that misuse accounted for 17.2% of overall use. Adults age 50 and older were more likely than younger adults to misuse benzodiazepines as a sleep aid, and to take them more often than prescribed.

Another study found that between 2000 and 2015, teenagers' exposure to benzodiazepines increased by 54%. Almost half of these exposures were documented as intentional overuse or misuse.

Combination Misuse

Substance use disorder is strongly associated with misuse of benzodiazepines. BZDs are most commonly overused or misused in combination with opioids and/or alcohol.


Benzodiazepines (BZDs) are tranquilizers that act as central nervous system depressants. They exert sedative effects, calm nerves, and reduce anxiety.

BZDs work by binding with inhibitory-GABA neurotransmitter receptors to block signals of anxiety and distress to the brain. Because of their rapid onset of action and ability to provide quick symptom relief, BZDs effectively treat anxiety, panic disorders, sleep issues, and seizures.

Despite their effectiveness, BZDs have the potential to be highly addictive, which can lead to misuse. Common side effects include drowsiness, dizziness, fatigue, and more.

A Word From Verywell

Benzodiazepine use can be controversial. While benzodiazepines have benefits and may be the best treatment option for some people, the potential for addiction and misuse presents significant risks. As with any prescription medication, it's important to discuss your concerns with a healthcare provider and weigh the risks and benefits associated with using benzodiazepines for your health.

Frequently Asked Questions

  • What are some common benzodiazepines?

    There are 15 different FDA-approved benzodiazepines on the market. Some common ones include Xanax, Valium, Klonopin, and Ativan.

  • Why are benzodiazepines addictive?

    The benzodiazepine class of drugs is addictive because they interact with GABA receptors in a way that causes dopamine to surge, increasing good feelings. Dopamine neurons in the brain's reward center play a vital role in making benzodiazepines addictive.

14 Sources
Verywell Health 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.
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By Christopher Bergland
Christopher Bergland is a retired ultra-endurance athlete turned medical writer and science reporter.