Valium vs Xanax

How they're similar

Diazepam and alprazolam are both benzodiazepines, a class of calming medicines. They share a long list of features, including their most important cautions.

• Both work quickly by strengthening GABA, the brain's main calming chemical messenger.
• Both treat anxiety.
• Both carry the two FDA boxed warnings, one about abuse, dependence, and withdrawal, and one about the danger of combining them with opioids.
• Both can cause physical dependence and tolerance with regular use, meaning the body adjusts to the drug over time.
• Both can cause dangerous withdrawal, including seizures, if stopped abruptly, so both must be tapered slowly with a prescriber.
• Both are sedating.
• Both are Schedule IV controlled substances, a federal category for drugs with a recognized potential for misuse.
• Both are generally used short-term, with SSRIs or SNRIs the first-line treatment for ongoing anxiety.
• Both are inexpensive generics.

How they differ

The drugs differ mainly in how long they last and what follows from that. The table below sums up the core points, with more detail underneath.

The clearest difference is duration. Diazepam is long-acting, with a long half-life, which is the time it takes the body to clear half a dose. The active substances the body makes from diazepam also stay in the body a long time. The result is a steady effect that lasts a long time. Alprazolam is short-acting, so it comes on and wears off quickly. That quick wear-off can mean more noticeable rebound anxiety, a return of anxiety symptoms between doses.

Because diazepam is long-acting, it can build up in the body. That is a particular reason for caution in older adults, who clear it slowly.

The two also differ in other uses. Diazepam is used for muscle spasm, certain seizures, and alcohol withdrawal, in addition to anxiety. Alprazolam is used mainly for anxiety and panic.

There is one more point worth noting on tapering. Because diazepam is long-acting, it is sometimes used to help people taper off shorter-acting benzodiazepines more smoothly.

Side effects compared

Both drugs are sedating, and both can cause drowsiness, reduced alertness, and slowed reactions. Because both strengthen GABA in the same way, their everyday side effects overlap closely.

The same serious cautions apply to both. Both can cause physical dependence and tolerance with regular use, and both can cause dangerous withdrawal, including seizures, if stopped abruptly. For that reason, neither should be stopped on its own, and both must be tapered slowly with a prescriber. Combining either drug with opioids is dangerous and is the subject of an FDA boxed warning.

Sleep, weight, and sexual effects

Both drugs are sedating, so both can cause drowsiness during the day. Diazepam's long action means its calming and sedating effect carries on longer, while alprazolam's effect is shorter.

These are not first-choice medicines for sleep, weight, or sexual concerns, and they are not intended as long-term treatments. Any effect that is troubling, including daytime sedation, is worth raising with a prescriber.

Why a clinician might choose one over the other

The choice often comes down to specifics.

A clinician might choose diazepam for a long, steady effect, or in the specific situations where its other uses apply, such as muscle spasm, certain seizures, or alcohol withdrawal.

Alprazolam is very commonly prescribed for anxiety and panic. Its short action and the rebound that can follow are a drawback for regular use.

Neither drug is a long-term solution for anxiety. For ongoing anxiety, an SSRI or SNRI is the first-line treatment.

The bottom line

Diazepam and alprazolam are the same class of drug, and the same serious cautions apply to both. The main difference is long-acting versus short-acting. For ongoing anxiety, the real question is usually whether a benzodiazepine is the right tool at all, compared with an SSRI or SNRI. That is a decision to make with a prescriber.

Sources

This guide draws on current prescribing information and public health references. It is reviewed for clinical accuracy and updated as guidance changes.

1. U.S. Food and Drug Administration. Diazepam prescribing information.
2. U.S. Food and Drug Administration. Alprazolam prescribing information.
3. MedlinePlus, U.S. National Library of Medicine.
4. National Institute of Mental Health. Mental health medications.