Benzodiazepine Equivalence Conversion (diazepam equivalents)
Converts between benzodiazepines and Z-drugs using approximate diazepam equivalents (Ashton Manual basis).
Formula
Equivalents are approximations drawn from the Ashton Manual; published sources vary up to two-fold for some agents. Equivalence ignores differences in half-life, potency per milligram and receptor profile.
Caveats & limitations
- Equivalents are approximate — treat as a starting point and adjust to response.
- Dose equivalence ignores half-life and receptor differences; withdrawal phenomena can still occur on switch.
- Switching for dependence/withdrawal should be gradual (typically 1/8 to 1/10 of the dose every 1–2 weeks).
- Z-drugs are included for reference only; they are not benzodiazepines but act at the same receptor complex.
Evidence & UK guidance
Primary evidence
Ashton H. Benzodiazepines: how they work and how to withdraw (The Ashton Manual). Newcastle upon Tyne: Newcastle University; 2002.
UK practice
The Ashton method — switching to an equivalent diazepam dose before a gradual taper — is the classic UK approach to benzodiazepine withdrawal, and the Maudsley Prescribing Guidelines give similar tables. NICE NG215 covers safe prescribing and withdrawal of dependence-forming medicines. Lorazepam remains preferred for acute agitation and status epilepticus protocols irrespective of equivalence.
Official resources
Formula and citations last verified: 2026-08-03