Medication guide

Clonazepam (Klonopin / Rivotril)

What is clonazepam?

Clonazepam is known as Klonopin in the United States, and in Japan it's sold as Rivotril or Landsen (リボトリール／ランドセン on Japanese packaging; two brands, same medicine). In the UK it is sold simply as clonazepam. It's a long-acting benzodiazepine: it calms overexcitable signalling in the brain, and a single dose keeps working for many hours.

How is it different from other anxiety medicines?

Long-acting: one dose covers many hours, with fewer of the between-dose dips that shorter medicines can have
Steady levels: it is cleared slowly, so its effect fades gently rather than dropping off
Covers several seizure types: including ones that start in early childhood
Two Japanese brands and several strengths: fine adjustments are easy

What is it used for in Japan?

Several types of epilepsy (the formal Japanese approval)

In the US, Klonopin is also approved for panic disorder; in Japan, the approval is epilepsy only. Using it for anxiety or panic here is off-label, so a Japanese doctor may suggest Japan-approved options instead. If you're arriving on Klonopin, bring your records.

How does it help?

It steadies overexcitable brain signalling for many hours at a time, which is what makes it useful against seizures. It does not need weeks to build up, although for epilepsy the dose is raised gradually. Like other benzodiazepines it can cause dependence with long-term daily use, so whether to use it, and for how long, is decided by weighing what it does for you against that risk; for epilepsy it is often taken long term, with the dose and the need for it reviewed by your doctor.

What should I tell my doctor before starting?

A few situations rule it out entirely; your doctor will choose something else if any of these apply:

A past allergic reaction to clonazepam
Acute narrow-angle glaucoma
Myasthenia gravis (a muscle-weakness condition)

And tell your doctor first if any of these apply; these usually just need adjustments or a closer eye:

Reduced breathing function
Other epilepsy medicines, such as phenytoin or valproate; blood levels or doses may need adjusting
Other sedating medicines, or regular alcohol use
Being older: a lower dose is usual, as unsteadiness and falls are more likely
Pregnant, planning to be, or breastfeeding (see the section below)

With long-term use, your doctor may check your liver, kidneys, and blood counts from time to time.

How do I take it, and what if I miss a dose?

Clonazepam is taken one to three times a day, usually starting low and increasing gradually.

If you miss a dose: take it when you remember, unless the next dose is close; in that case just skip it. Never double up
Keep to a regular routine: this matters most when it is controlling epilepsy, because a sudden drop in the dose can bring on seizures
Alcohol: avoid it; the Japanese label advises against combining the two, since it deepens the drowsiness

What side effects should I expect?

Most are mild. Not everyone gets them.

Drowsiness (around 25%): mostly early and after dose increases; it often eases as your body adjusts
Unsteadiness (around 15%): take care on your feet
Tiredness or slowed thinking, in some people
A wheeze, and sometimes more saliva (the label flags both in infants and young children)

If anything is bothering you, tell your doctor; there's often a way to adjust.

Finally, one thing that is rare, and avoidable:

Combined with alcohol or other sedatives, the drowsiness can run deeper than expected; if you ever feel unusually heavily sedated or your breathing feels slowed, call us the same day. Taken as prescribed, without alcohol, this is very unlikely

Will I become dependent? How do I stop safely?

Like other benzodiazepines, it can be habit-forming with regular long-term use, and because it is often taken for years, the Japanese label asks doctors to watch for tolerance. The body gets used to it, and stopping suddenly after regular use can cause withdrawal, including rebound anxiety, sleeplessness, tremor, and, in some cases, seizures; if it's controlling epilepsy, a sudden stop can bring on prolonged seizures. So never stop suddenly on your own. Because of its long action it is sometimes used to make a taper steadier; your doctor steps it down gradually, in small steps, and if it was prescribed for anxiety or panic and has been taken daily for a long time, the plan usually moves toward reducing it, agreed with your doctor.

Can I bring it into Japan?

Yes, within limits, because it's a controlled medicine here. Clonazepam is a scheduled (psychotropic) medicine in Japan: a personal supply of roughly up to a month travels with you without any advance paperwork, larger amounts need paperwork arranged before you travel, and mailing it to Japan is prohibited. It also cannot be prescribed online, at a first visit or a follow-up, until a doctor in Japan has examined you in person for that condition, so if you're arriving on Klonopin, plan an in-person visit and bring enough supply to bridge.

Can I drive while taking it?

No; avoid driving while you're taking it. Clonazepam can cause drowsiness and slow your attention and reactions, and the Japanese label instructs that patients taking it should not drive or operate dangerous machinery. Its long action means this applies through the day, not just after a dose.

What about pregnancy and breastfeeding?

Avoided where possible in pregnancy, and the Japanese label says to avoid breastfeeding while taking it; tell your doctor early and we'll find the safest plan together. The label allows clonazepam in pregnancy only when the benefit, such as preventing frequent seizures that would harm the baby, outweighs the risk, and it passes into breast milk, where it can cause pauses in a newborn's breathing. If it's controlling epilepsy or long-standing anxiety, don't stop suddenly on learning you're pregnant; contact your doctor promptly and the plan is adjusted safely. Our guides to medication in pregnancy and medication while breastfeeding cover the wider picture.