Diazepam

Is diazepam safe?

For a few days of severe anxiety, a painful muscle spasm or supervised alcohol withdrawal, diazepam is an effective and well-understood medicine, and an overdose of diazepam alone very rarely kills an adult. The risks come with time and company: it builds up in the body, dependence develops with daily use, older people are prone to falls and confusion, and mixed with opioids or alcohol it can stop breathing. We score it 39, close to alprazolam (40), lorazepam (41) and clonazepam (39).

How long does diazepam last?

Diazepam is broken down by two liver enzymes, CYP3A4CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary and CYP2C19, into active products, including desmethyldiazepam, temazepam and oxazepam. The label gives a half-life of up to 48 hours for diazepam itself and up to 100 hours for desmethyldiazepam. With daily dosing, each dose adds to what is still there from earlier ones, so levels build up over days.

That long tail causes most trouble in older adults. The label reports extensive build-up of diazepam and desmethyldiazepam in healthy older men on long-term treatment, and asks for a starting dose of 2 to 2.5 mg once or twice a day to avoid unsteadiness and over-sedation.

Doses on the US label

In the UK, the NHS says diazepam should only be used short term, up to 4 weeks. Diastat rectal gel and Valtoco nasal spray are separate products that carers give for clusters of seizures.

Interactions that catch people out

Because two enzymes clear it, diazepam has more drug interactions than lorazepam. The label names cimetidine, ketoconazole, fluvoxamine, fluoxetine and omeprazole as drugs that can raise levels and lead to longer, deeper sedation. Omeprazole is also sold over the counterOver-the-counterA medicine you can buy without a prescription, in a pharmacy or shop, with directions on the pack for safe use without a doctor.More in the glossary, so tell your pharmacist about every medicine you take, including ones bought without a prescription.

Alcohol, opioids, sleeping pills, sedating antihistamines, antipsychotics and other sedatives all add to diazepam's effect on the brain and breathing; the label says alcohol is not recommended at all.

Dependence, withdrawal and the 2020 warning

Since 2020 the FDA's boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary for all benzodiazepines has covered abuse, misuse, addiction, physical dependenceDrug dependenceThe body's adaptation to a drug taken regularly, so that stopping it suddenly causes withdrawal symptoms. It is not the same as addiction.More in the glossary and withdrawal. The risk grows with higher doses and longer courses. Stopping abruptly or cutting quickly can cause withdrawal reactions that can be life-threatening, and some people have symptoms for more than 12 months. The label asks for a gradual taper, paused or slowed if symptoms appear.

Overdose and mixing with opioids

In CDC data from 23 US states, 92.7% of benzodiazepine overdose deaths in the first half of 2020 also involved an opioid, mostly illicit fentanyl. In England and Wales, diazepam was mentioned on 302 drug-poisoning death records registered in 2024, 5.4% of the total, making it the benzodiazepine most often found (ONS). Most such deaths involve several drugs. Illicit benzodiazepines also appear: bromazolam was mentioned on 169 records in 2024. Tablets bought outside a pharmacy may not be what they claim.

Signs of a dangerous overdose include extreme sleepiness, confusion, slurred speech, poor coordination, slow breathing and being hard to wake. Call emergency services. If opioids might be involved, give naloxone: it will not reverse diazepam but can reverse the opioid. US Poison Help is 1-800-222-1222.

Who should be careful

Talk to your doctor or pharmacist before taking diazepam if you are over 65 or have kidney or liver disease; take an opioid, a sleeping pill such as zolpidem, gabapentin, pregabalin or one of the interacting drugs above; drink regularly; have sleep apnoea, lung disease, depression or a history of substance use; or are pregnant. Do not drive until you know how it affects you, and remember the effect can last into the next day. A low score is not a reason to stop a prescribed medicine on your own; withdrawal is one of the main risks.

How we scored it

Track record (95) is the strongest factor after more than 60 years of use. Dependence (15) and regulatory warnings (20) sit in the lowest band because of the class boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary. Interactions (25) score below lorazepam's because two liver enzymes clear diazepam. Overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (40) reflects a drug very rarely fatal alone, and serious side effects (45) reflect build-up and falls in older people.