What Is A Lethal Dose Of Valium (Diazepam)?

Medically Reviewed by Johnelle Smith, M.D.

Updated on March 31, 2026

There is no known lethal dose of Valium (diazepam). There have been few cases of fatal overdose caused by Valium alone, but dangerous overdoses can occur when Valium is taken in combination with opioids or alcohol.

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Valium (diazepam) is a prescription medication that belongs to a class of drugs called benzodiazepines, which are prescribed to treat anxiety, panic disorders, muscle spasms, and seizures. This medication works by slowing down the central nervous system and producing calming effects that help people feel relaxed and less anxious. While Valium can be very effective when used as prescribed by a doctor, it has significant potential for abuse and can become dangerous when misused or taken with other substances.

People often abuse Valium because it produces feelings of relaxation, drowsiness, and euphoria, especially when taken in higher doses than prescribed or when combined with alcohol or other drugs. The medication can be particularly deadly because it depresses breathing and heart rate, and when mixed with alcohol or opioids, this effect becomes much more dangerous and can lead to fatal overdoses. While there is no known lethal dose of diazepam in humans, some animal testing has given insight into what a fatal amount of Valium is.

In animal testing, the following lethal doses were found:

  • rats: 1,200 milligrams per kilogram (mg/kg)
  • dogs: 1,000 mg/kg
  • mice: 700 mg/kg

Learn more about the lethal dose of commonly abused drugs

Has Anyone Died From Valium (Diazepam) Overdose?

Fatal Valium overdose is extremely rare. In a survey of 914 benzodiazepine-related deaths in North America, only two cases involved diazepam alone.

In instances in which people have intentionally ingested up to 2,000 mg of diazepam, people recovered within 48 hours without any serious complications. Most cases involving a fatal Valium overdose also involve other substances such as opioids, alcohol, or other central nervous system depressants.

Lethal Consequences Of Combining Valium With Alcohol Or Opioids

One of the most dangerous aspects of Valium abuse involves combining it with other depressant substances, particularly alcohol and opioids. While fatal overdoses from Valium alone are uncommon, the risk of death increases when it’s mixed with other substances that also slow down the central nervous system. These dangerous combinations are responsible for a significant number of accidental overdose deaths each year.

Mixing alcohol and Valium can cause:

  • Slowed Heartbeat: the combination can cause the heart rate to drop to dangerously low levels, reducing blood flow to vital organs and potentially leading to cardiac arrest
  • Confusion: mental impairment becomes severe, making it difficult for people to recognize they’re in danger or seek help when experiencing an overdose
  • Respiratory Depression: breathing can slow down significantly or stop altogether, which is often the direct cause of death in these overdoses
  • Loss of Consciousness: people may fall into a coma-like state where they cannot wake up or respond to attempts to rouse them

Taking diazepam in combination with opioids also creates an extremely high risk of respiratory depression, as both drugs suppress the brain’s ability to control breathing. The unpredictability of these interactions means that even people with tolerance to one or both substances can accidentally overdose, making it a very risky proposition to combine Valium, opioids, and alcohol.

Symptoms And Signs Of A Valium (Diazepam) Overdose

Diazepam is a relatively safe medication because the toxic-to-therapeutic ratio of benzodiazepines is very high.

A toxic-to-therapeutic ratio compares the blood concentration at which a drug is toxic with the concentration at which the drug is effective. However, if you or a loved one use Valium, it’s important to be aware of the signs of overdose.

A mild overdose may manifest itself through:

  • lethargy
  • drowsiness
  • confusion
  • dizziness
  • lack of alertness
  • rash
  • rapid eye movements

More serious overdoses may involve difficult or labored breathing, along with blue-colored lips and fingernails that show the body isn’t getting enough oxygen. The person may have trouble speaking clearly, stumble when trying to walk, and lose control of their movements due to coordination problems. They might also develop dangerously low blood pressure and weak, floppy muscles that make it hard to move or stay upright. In the worst cases, these symptoms can lead to a coma where the person becomes unconscious and unresponsive, and if emergency medical help isn’t received right away, the overdose can result in death.

What To Do If You Suspect A Valium Overdose

If you suspect someone has overdosed on Valium, call 911 immediately. This is especially urgent if the person has also taken alcohol, opioids, or other depressants alongside Valium. While waiting for help to arrive, try to keep the person awake and breathing. If they are unconscious, place them on their side to prevent choking and stay with them until emergency responders arrive.

Be honest with emergency responders about what substances were taken and how much, as this information can be life-saving. Many states have Good Samaritan laws that protect people who call 911 to report an overdose, so fear of legal consequences should never stop someone from making that call. If the person survives, professional addiction treatment should be the next step.

This page does not provide medical advice. See more

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