Why the Ashton Manual Recommends Switching to Diazepam Before a Benzo Taper

Key Takeaways

• The Ashton Manual advises people on short-acting benzodiazepines to switch to diazepam (Valium) before tapering, because diazepam leaves the body slowly and comes in small strengths.
• Short-acting benzodiazepines such as alprazolam (Xanax) and lorazepam (Ativan) rise and fall in the blood several times a day, and many people feel a small withdrawal between doses.
• The switch is a tapering method and not a trade of one drug for another, because the diazepam itself is then tapered.
• The changeover is made gradually, one dose at a time, and the opening stages usually aim for an approximately equivalent dose rather than a reduction.
• Diazepam can be sedating, and the full effect of a new dose can take a week or more to show, which is the reason to hold at each stage.
• Not everyone needs the switch, since a person already taking diazepam does not, and some people reduce the medication they already take instead.
• The crossover is offered to the patient as an option, and the plan is worked out with the prescriber, never copied from a page.
• A benzodiazepine should never be stopped suddenly, and a seizure is a medical emergency that calls for 911.

Why does the Ashton Manual switch people to diazepam before a benzo taper?

Because diazepam (Valium) leaves the body slowly, and because it comes in small doses. Those are the two reasons Professor C. Heather Ashton gives in Chapter II of the Ashton Manual.

Her advice is aimed at people who take potent, short-acting benzodiazepines such as alprazolam (Xanax) and lorazepam (Ativan). With those drugs, she wrote, a smooth decline in blood and tissue levels cannot be achieved. So, the Manual changes the drug first and reduces the dose second, a method known as a crossover taper.

Some people hear “switch to Valium” and worry that one drug is simply being traded for another. That is not what happens. A person who took a benzodiazepine as prescribed, and whose nervous system adapted to it, has physical dependence, and dependence is not addiction. The crossover is a tapering tactic that makes the reductions smaller and steadier, and the diazepam itself is then tapered.

What makes a short-acting drug so hard to taper, and what does diazepam do differently?

Short-acting benzodiazepines rise and fall several times a day.

Table 1, in the first chapter of the Manual, lists a half-life of 6 to 12 hours for alprazolam and 10 to 20 hours for lorazepam. Half-life is the time the blood level takes to fall to half its peak after a single dose. A drug that clears this quickly is taken several times a day, and the level climbs and drops between doses.

Chapter II describes those peaks and troughs and notes that many people feel a small withdrawal between each dose. Patients call it interdose withdrawal. The anxiety returns late in the morning, or sleep breaks in the small hours, shortly before the next tablet is due.

A taper laid on top of that pattern is hard to read. Was the bad afternoon caused by last week’s reduction, or by the ordinary dip before the evening dose? Often, nobody can tell.

Diazepam leaves the body slowly, so the blood level falls smoothly.

The same table gives diazepam a half-life of 20 to 100 hours, and 36 to 200 hours for its active metabolite, the compound the body converts it into. In Chapter II, Professor Ashton does the arithmetic. With a half-life of up to 200 hours, the blood level from each dose falls by only half in about 8.3 days.

That slowness is the point. One dose overlaps the next, the troughs fill in, and when the dose is lowered the level drifts down instead of dropping.

The Manual says this allows the body to adjust slowly to a decreasing concentration. So, after the crossover, each reduction can be judged on its own.

The 2 mg tablet is the second reason.

A slow taper needs small steps, and most tablets do not allow them. The Manual points out that the smallest lorazepam tablet, 0.5 mg, and the smallest alprazolam tablet, 0.25 mg, are each equivalent to 5 mg of diazepam.

Diazepam comes in 2 mg tablets that are scored down the middle and easily halved into 1 mg doses. Professor Ashton calls it the only benzodiazepine that is ideal for this purpose.

Think of pocket change. With four quarters, a dollar can only be handed over 25 cents at a time. With a hundred pennies, it can be handed over as slowly as a person likes.

The Manual also mentions liquid preparations measured with a graduated syringe. In the United States, diazepam is made as an oral solution that holds 1 mg in each milliliter, which allows steps smaller than half a tablet. Small units matter more as a taper goes on. The Maudsley Deprescribing Guidelines describe hyperbolic reductions, in which each step gets smaller as the dose gets lower.

What about switching from Xanax to Ativan instead?

A move from alprazolam to lorazepam is sometimes suggested as the long-acting choice. It is not. Table 1 lists lorazepam at 10 to 20 hours, and Chapter II names it beside alprazolam among the short-acting drugs.

Its smallest tablet is no finer in diazepam terms, so neither problem is solved. The Manual’s example schedules cross both drugs to diazepam.

How is the switch to diazepam done?

Gradually. Chapter II says the changeover is usually carried out in stepwise fashion, substituting one dose at a time. The evening or night-time dose is usually replaced first, and the other doses follow one by one, at intervals of a few days or a week.

In the opening stages, the aim is usually an approximately equivalent dose, not a reduction. The notes to the Manual’s first example schedule allow a week at each of those stages, or two weeks for anyone who prefers. Each new arrangement is held for that week or two before the next dose is replaced.

Going one dose at a time has a second purpose. The Manual says it helps to find the equivalent dose for that individual, which no table can predict exactly. It adds that the replacement need not always be complete, because a person who sleeps well on slightly less diazepam than the table calls for has already made a first reduction.

From there, the reductions come in steps of up to one tenth of the dose, and in the Manual’s higher-dose examples they begin before the last of the original drug has been replaced. The pace belongs to the person taking the medication, and the plan is worked out with the prescriber, not copied from a page.

Unfortunately, the switch has trade-offs, and the Manual names them.

First, the equivalence figures are approximate. Table 1 lists 0.5 mg of alprazolam and 1 mg of lorazepam as each roughly equivalent to 10 mg of diazepam, and its footnote says the figures are based on clinical experience and may vary between individuals. The number on the bottle rises because diazepam is less potent per milligram, not because the dose is larger.

Professor Ashton also wrote that many people have suffered because they were switched suddenly to a different drug at an inadequate dose. A separate article explains how to read the Ashton Manual conversion chart.

Second, diazepam can be sedating. The Manual notes that lorazepam seems to have less hypnotic, or sleep-inducing, activity than diazepam, so a person moved all at once to the full equivalent dose is liable to become extremely sleepy. Fortunately, a stepwise changeover leaves room to adjust. The aim in the schedule notes is a dose that avoids withdrawal symptoms but is not so great as to cause sleepiness.

Third, a slow drug gives slow feedback. The first chapter notes that diazepam accumulates with repeated daily dosing. So, the full effect of a new dose, or of a reduction, can take a week or more to show. That is the reason to hold at each stage.

Who does not need to switch?

A person already taking diazepam does not. The Manual’s Schedule 2 is a simple withdrawal from diazepam itself. The notes to Schedule 11 say the same of chlordiazepoxide (Librium): because it is long-acting, there is no need for diazepam substitution.

Half-life is not the only test, however. Clonazepam (Klonopin) has a half-life of 18 to 50 hours in Table 1, yet the Manual’s schedules still cross it to diazepam. A potent drug in a small tablet is hard to cut finely. The Manual also acknowledges that some people have particular difficulty with that switch, and describes specially made capsules for reducing clonazepam directly.

The one stated exception runs the other way. Triazolam (Halcion) has a half-life of about 2 hours, and Professor Ashton wrote that a person taking it is practically withdrawn each day. In her view it could be stopped without a long-acting substitute, with a short course of diazepam if withdrawal symptoms followed, and she applied the same approach to the sleep medications zolpidem and zaleplon.

Dr. Leeds does not treat that exception as a rule for a person who has taken a sleeping pill nightly for years. After about four weeks of regular use, he does not stop a benzodiazepine or a z-drug abruptly. For triazolam, as for other benzodiazepines, he generally prefers a diazepam crossover and a gradual taper.

The 2020 United States Food and Drug Administration (FDA) boxed warning update says that stopping a benzodiazepine abruptly, or reducing the dose too quickly, can cause life-threatening withdrawal reactions, including seizures. A seizure is a medical emergency: call 911.

The crossover is offered, not imposed.

Informed consent applies to the switch as much as to the taper. The risks come first, sedation and an imperfect conversion among them. Then come the alternatives, such as reducing the current drug directly or staying at the present dose for now. Before the first dose is replaced, patient and doctor also agree on a plan for coming off the diazepam.

The person can decline, or change course later. If the diazepam proves too sedating, the doctor must slow the changeover or adjust the dose. If it is going well, patient and doctor may agree to move on to the next stage.

Dr. Leeds’ practice in Fort Lauderdale offers medically supervised benzodiazepine and z-drug tapering for patients in Florida. It is a concierge practice, not an insurance practice, and he works directly with each patient, using the crossover to diazepam where it helps and a direct taper where it does not. Contact the office to ask whether a crossover makes sense before a taper.

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.