Key Takeaways
- The Ashton Manual’s equivalence table is Table 1 in its first chapter, and it lists for each benzodiazepine the oral dose Professor C. Heather Ashton considered roughly equal to 10 mg of diazepam (Valium), with each drug’s half-life beside it.
- By that table, 0.5 mg of alprazolam (Xanax), 0.5 mg of clonazepam (Klonopin) and 1 mg of lorazepam (Ativan) are each roughly equal to 10 mg of diazepam.
- The figures are approximate, and the Manual’s own footnote says they are firmly based on clinical experience but may vary between individuals.
- Equal strength is not equal duration. Lorazepam’s half-life is 10 to 20 hours while diazepam’s is 20 to 100 hours, with a longer-lived active metabolite, and that is why the Manual chose diazepam for the crossover.
- Benzodiazepines all act at the same GABA (gamma-aminobutyric acid) receptor, so they are cross-tolerant, and that shared adaptation is what makes a diazepam crossover possible.
- In the Manual’s method the table is used to exchange one dose at a time for diazepam, usually starting with the night-time dose, with a hold of a week or two between exchanges. The equivalent dose is settled with the prescriber by symptoms rather than by arithmetic.
- The table is a map rather than a schedule. It says how much diazepam stands in for another drug and nothing about the pace of reduction afterward, which belongs to the person tapering and their prescriber.
- Never stop a benzodiazepine abruptly, because a sudden loss of the drug can bring severe withdrawal including seizures. A seizure is a reason to call emergency services.
In short: the Ashton Manual’s equivalence table (Table 1, Chapter I) lists, for each benzodiazepine, the oral dose roughly equal to 10 mg of diazepam (Valium), plus its half-life. Examples: alprazolam (Xanax) 0.5 mg, clonazepam (Klonopin) 0.5 mg, lorazepam (Ativan) 1 mg. The figures are approximate, people vary, and equal strength does not mean equal duration: alprazolam lasts 6 to 12 hours, diazepam 20 to 100. The table is used to plan a switch to diazepam, not to set a schedule. The conversion calculator applies it.
What does the Ashton Manual’s equivalence table actually show?
The Ashton Manual’s equivalence table lists benzodiazepines with, beside each one, the oral dose that Professor C. Heather Ashton considered roughly equal to 10 mg of diazepam. It is Table 1 in Chapter I of the Manual (the Manual’s full title is “Benzodiazepines: How They Work and How to Withdraw”), and benzo.org.uk also serves it as a page of its own. Each row carries a second figure, the drug’s half-life, and that figure matters as much as the first.
The table was written for the person taking the drug. Chapter II says that most of the Manual’s readers are planning to manage their own withdrawal with their doctor’s cooperation. Nearly always, that reader took a benzodiazepine as prescribed and became physically dependent on it.
Dependence is not addiction. It is the nervous system’s adaptation to a drug, and the table exists to help reverse that adaptation without a sudden drop in the drug’s effect.
The table, as the Manual gives it.
The table below reproduces the Manual’s Table 1. Half-life is in hours, with the half-life of a long-lasting active metabolite in parentheses where the Manual uses brackets, and the four z-drugs close the table as they close the Manual’s.
| Drug | Brand names in the Manual | Dose equivalent to 10 mg diazepam | Half-life (hours) |
|---|---|---|---|
| Alprazolam | Xanax, Xanor, Tafil | 0.5 mg | 6 to 12 |
| Bromazepam | Lexotan, Lexomil | 5 to 6 mg | 10 to 20 |
| Chlordiazepoxide | Librium | 25 mg | 5 to 30 (36 to 200) |
| Clobazam | Frisium | 20 mg | 12 to 60 |
| Clonazepam | Klonopin, Rivotril | 0.5 mg | 18 to 50 |
| Clorazepate | Tranxene | 15 mg | (36 to 200) |
| Diazepam | Valium | 10 mg | 20 to 100 (36 to 200) |
| Estazolam | ProSom, Nuctalon | 1 to 2 mg | 10 to 24 |
| Flunitrazepam | Rohypnol | 1 mg | 18 to 26 (36 to 200) |
| Flurazepam | Dalmane | 15 to 30 mg | (40 to 250) |
| Halazepam | Paxipam | 20 mg | (30 to 100) |
| Ketazolam | Anxon | 15 to 30 mg | 30 to 100 (36 to 200) |
| Loprazolam | Dormonoct | 1 to 2 mg | 6 to 12 |
| Lorazepam | Ativan, Temesta, Tavor | 1 mg | 10 to 20 |
| Lormetazepam | Noctamid | 1 to 2 mg | 10 to 12 |
| Medazepam | Nobrium | 10 mg | 36 to 200 |
| Nitrazepam | Mogadon | 10 mg | 15 to 38 |
| Nordazepam | Nordaz, Calmday | 10 mg | 36 to 200 |
| Oxazepam | Serax, Serenid, Serepax, Seresta | 20 mg | 4 to 15 |
| Prazepam | Centrax, Lysanxia | 10 to 20 mg | (36 to 200) |
| Quazepam | Doral | 20 mg | 25 to 100 |
| Temazepam | Restoril, Normison, Euhypnos | 20 mg | 8 to 22 |
| Triazolam | Halcion | 0.5 mg | 2 |
| Non-benzodiazepines with similar effects (z-drugs) | |||
| Zaleplon | Sonata | 20 mg | 2 |
| Zolpidem | Ambien, Stilnoct, Stilnox | 20 mg | 2 |
| Zopiclone | Zimovane, Imovane | 15 mg | 5 to 6 |
| Eszopiclone | Lunesta | 3 mg | 6 (9 in older adults) |
The numbers are approximate, and the Manual says so.
Professor Ashton did not present these figures as exact conversions. The footnote to the table, as benzo.org.uk serves it, reads: “These equivalents do not agree with those used by some authors. They are firmly based on clinical experience during switch-over to diazepam at start of withdrawal programs but may vary between individuals.” Chapter II repeats the caution in one line: the equivalents are only approximate and differ from person to person.
Chapter I notes that equivalent doses vary as much as twenty-fold, which is why even approximations are worth having. A doctor who does not know that half a milligram of alprazolam matches ten milligrams of diazepam can move a patient onto a less potent drug in far too small a dose, and Chapter II says many people have suffered exactly that. The table is a guard against one specific error, not a claim of exactness.
Equal strength is not equal duration.
Half-life is the time it takes for the blood level of a drug to fall by half after a single dose, and the Manual’s footnote says that this too varies considerably between people. Lorazepam’s half-life is 10 to 20 hours. Diazepam’s is 20 to 100 hours, its active metabolite stays for 36 to 200 hours, and Chapter II describes the level after a dose falling by half in about eight days.
So 1 mg of lorazepam and 10 mg of diazepam are equal in strength but not in duration. The lorazepam level falls fast within hours, which is why the Manual says a short-acting drug can leave a person in a mini-withdrawal between doses, while the diazepam is still at work a week later. That slow, smooth fall in blood level, and scored tablets that can be split, is why the Manual chose diazepam for the crossover.
Strength decides the switch. Duration decides the smoothness.
Why benzodiazepines are cross-tolerant.
Chapter I of the Manual explains that all benzodiazepines act by enhancing GABA (gamma-aminobutyric acid), the brain’s main calming chemical, at the same receptor. The drugs differ in potency and in how long they last, not in what they do, so a nervous system that has adapted to one of them has adapted to the mechanism itself.
That shared adaptation is called cross-tolerance, and it is what makes a diazepam crossover possible. As far as the receptors are concerned, diazepam taking over from alprazolam or lorazepam is a change of drug, not a loss of drug.
Cross-tolerance is also why the figures are starting points and never guarantees to the milligram. Tolerance develops at different rates to the different effects of these drugs, the Manual notes, so too sleepy means the figure was generous, withdrawal symptoms mean it was thin, and the next exchange is adjusted with the prescriber. Symptoms settle the equivalent, not arithmetic.
How the table is used in a crossover taper.
Chapter II describes a stepwise exchange, one dose at a time, and the Manual suggests making the first substitution in the night-time dose. A person taking a short-acting drug three times a day replaces one of those doses with its diazepam equivalent, holds for a week or two, then replaces the next. This site’s article on the Ashton Manual diazepam switch walks through that exchange.
The Manual’s own example is someone taking 2 mg of lorazepam three times a day, a full equivalent of 60 mg of diazepam. Switched there all at once, that person is liable to become extremely sleepy, and switched suddenly to a much smaller dose, they will probably get withdrawal symptoms. One dose at a time avoids both.
Only when every dose has become diazepam does the reduction begin. Unless the starting dose is very large, the Manual says, there is no need to aim for any reduction during the exchange.
The table is a map, not a schedule.
A map shows where two places stand in relation to each other, not how fast to travel between them. The equivalence table says how much diazepam stands in for a dose of another drug, and nothing about the pace of reduction afterward. That pace belongs to the person tapering and their prescriber, as this site’s article on patient-directed tapering explains.
Nothing in the table licenses a fast switch, and nothing in the Manual licenses a fast taper. A benzodiazepine is never stopped abruptly, because a sudden loss of the drug can bring severe withdrawal, including seizures, and the Food and Drug Administration’s 2020 benzodiazepine label update carries the same warning. Call emergency services for a seizure or any medical emergency.
What the reduction looks like on paper.
After the exchange, the diazepam comes down in small amounts at intervals the person tolerates, with the steps getting smaller as the dose gets lower, and no one’s actual doses belong on a page like this. Hyperbolic tapering and the Maudsley Deprescribing Guidelines have since made that last feature explicit, each reduction a fraction of the current dose rather than a fixed amount, and in this site’s view that is a development in the direction Professor Ashton’s schedules already point.
The benzodiazepine taper calculator and the Ashton Manual Guide calculator on this site both start from the Manual’s equivalents and lay out a stepwise reduction shape, as planning tools for a conversation with a prescriber rather than instructions. The guide to starting a gradual benzodiazepine taper covers what comes before the first step.
Read with its footnote, the table says what Professor Ashton meant it to say: roughly this much for that much, one dose at a time, and then the slow part begins.
Common questions about the equivalence table.
What is the Ashton Manual benzodiazepine equivalence table?
It is Table 1 in Chapter I of the Ashton Manual, listing benzodiazepines and z-drugs with the oral dose of each that is approximately equal to 10 mg of diazepam, alongside each drug’s half-life.
How do I use a benzo equivalence table?
It gives the diazepam equivalent of a dose of another benzodiazepine. In the Manual’s method, that figure is used to exchange one dose at a time for diazepam over several weeks, with a prescriber, before any reduction begins. It does not set the pace of the taper.
How much diazepam is equivalent to my benzo?
By the Manual’s table, 0.5 mg of alprazolam, 0.5 mg of clonazepam, 1 mg of lorazepam, 20 mg of oxazepam, 20 mg of temazepam, 25 mg of chlordiazepoxide, and 10 mg of nitrazepam are each roughly equal to 10 mg of diazepam. The figures vary from person to person, so the equivalent for one person is settled with a prescriber during the switch. The benzodiazepine conversion calculator on this site does this arithmetic for any drug in the table.
Are benzodiazepine equivalence tables accurate?
They are accurate as approximations, and no table claims more. The Manual’s figures differ from some other authors’ and vary from person to person, and the equivalent dose says nothing about duration, so two doses of equal strength can behave differently across a day. That is why the table prints half-life beside each figure.
This article is educational. It is not medical advice, and reading it does not create a doctor-patient relationship. Decisions about starting, continuing, or tapering any medication should be made with your own physician.
