Clonazepam belongs to a group of medicines called benzodiazepines.
Clonazepam is available on prescription only. It comes as tablets and as a liquid that you swallow.
- Clonazepam works by increasing levels of a calming chemical in your brain. This can relieve anxiety, stop seizures and fits or relax tense muscles.
- The most common side effect is feeling sleepy (drowsy) during the daytime.
- Clonazepam is not likely to be addictive if you take it for a short time (2 to 4 weeks).
- If you take clonazepam for more than 2 to 4 weeks, your dose will need to be reduced gradually before you stop taking it.
- Do not drink alcohol while taking clonazepam. There's a risk you can sleep very deeply and you may have trouble waking up.
Who can and cannot take clonazepam
Clonazepam tablets and liquid can be taken by adults aged 18 years and over.
It can also be taken by children from 1 month old for epilepsy.
It's not suitable for everyone.
To make sure it's safe for you, tell your doctor before starting clonazepam if you:
- have had an allergic reaction to clonazepam or any other medicine in the past
- have myasthenia gravis, a condition that causes muscle weakness
- have sleep apnoea, a condition that causes breathing problems when you're asleep
- have lung, liver or kidney problems
- have spinal or cerebellar ataxia (where you may become shaky and unsteady and have slurred speech)
- have (or have had) problems with alcohol or drugs
- have recently had a loss or bereavement, depression or thoughts of harming yourself or suicide
- have been diagnosed with a personality disorder
- are trying to get pregnant, are already pregnant or breastfeeding
- are going to have a general anaesthetic for an operation or dental treatment
How and when to take it
It's important to take clonazepam exactly as your doctor tells you to.
You'll usually start on a low dose and gradually increase it over 2 to 4 weeks until your doctor thinks the dose is the right dose.
Your doctor will tell you if you need to take clonazepam in 1 dose or split your dose so you take it up to 3 times each day. Ask a doctor or pharmacist if you're not sure how to take it.
The usual dose for:
- epilepsy in adults – the starting dose is 1mg taken at night (increasing to 4mg to 8mg over 2 to 4 weeks)
- epilepsy in children – the dose varies depending on their age. It will be increased gradually over 2 to 4 weeks
- involuntary muscle spasms (adults) – the starting dose is 1mg taken at night (increasing to 4mg to 8mg over 2 to 4 weeks)
- panic disorder – 1mg to 2mg each day
- restless legs syndrome – 500 micrograms to 2mg each day
If you're older than 65 or have kidney, liver or severe breathing problems, your doctor may recommend a lower dose.
Take clonazepam tablets with a drink of water. You can take the tablets or liquid with or without food.
What if I forget to take it?
If you forget to take your clonazepam, take it as soon as you remember, unless it's nearly time for your next dose.
In this case, just leave out the missed dose and take your next dose as usual.
Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.
If you forget doses often, it may help to set an alarm to remind you.
You could also ask a pharmacist for advice on other ways to remember your medicines.
What if I take too much?
The amount of clonazepam that can lead to an overdose varies from person to person.
If you take too much clonazepam, you may get symptoms including:
- poor coordination or trouble speaking
- feeling sleepy
- a slow or irregular heartbeat
- uncontrolled eye movements
- muscle weakness
- feeling overexcited
If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.
Take the clonazepam packet, or the leaflet inside it, plus any remaining medicine with you.
Like all medicines, clonazepam can cause side effects in some people, but many people have no side effects or only minor ones.
Common side effects
These common side effects happen in more than 1 in 100 people.
If you get these side effects, keep taking the medicine and speak to a doctor if they bother you or do not go away:
- disturbed sleep (such as vivid dreams)
- feeling sleepy (drowsy) in the daytime
- feeling light-headed, unsteady or dizzy
- muscle weakness
Serious side effects
It happens rarely, but some people can have serious side effects when taking clonazepam.
Tell a doctor straightaway if:
- your breathing becomes very slow or you have short, shallow breaths
- your skin or the whites of your eyes turn yellow – this could be a sign of liver problems
- you find it difficult to remember things (amnesia) or are confused
- you see or hear things that are not there (hallucinations) or think things that aren't true (delusions)
- problems with your coordination or controlling your movements
- you have swollen ankles, a racing heartbeat, cough and feel tired – this could be a sign of heart problems
- you bruise easily, feel tired, have nosebleeds and have breathlessness – this can be a sign of blood problems
- you notice mood changes such as talking too much, feeling overexcited, restless, irritable or aggressive (mood changes can become serious and are more likely in children and people over 65 years old)
Serious allergic reaction
In rare cases, clonazepam may cause a serious allergic reaction (anaphylaxis).
These are not all the side effects of clonazepam. For a full list, see the leaflet inside your medicine packet.
You can report any suspected side effect to the UK safety scheme.
How to cope with side effects
What to do about:
- disturbed sleep (such as vivid dreams) – speak to a doctor; they may suggest a different medicine or a lower dose.
- feeling sleepy (drowsy) in the daytime – this should get better after a week or so but speak to a doctor; they may suggest a lower dose. Do not drive, ride a bike or use machinery or tools until you feel better.
- feeling lightheaded, unsteady or dizzy – try to lie down or sit down. Do not drive, ride a bike or use machinery or tools until you feel better. If you still have these side effects after a week or they get worse, speak to a doctor.
- muscle weakness – try to sit down if you feel weak. If you still have these side effects after a week or so, or if they get worse, speak to a doctor.
Pregnancy and breastfeeding
Clonazepam is not usually recommended during pregnancy. There's not enough information to know if it's safe, and it might mean your baby is born with withdrawal side effects.
If you become pregnant while taking clonazepam, speak to a doctor. Do not stop taking clonazepam suddenly if you have been taking it regularly.
Your doctor can explain the risks and benefits of taking clonazepam and will help you choose the best treatment for you and your baby.
You may need to keep taking clonazepam during pregnancy as it's important for you to remain well.
Clonazepam and breastfeeding
Clonazepam is not recommended while breastfeeding.
If you're breastfeeding or want to breastfeed, talk to a doctor or pharmacist, as there might be better medicines for you. It will depend on what you're taking clonazepam for.
If your doctor says it's OK to take clonazepam while breastfeeding and you notice that your baby's not feeding as well as usual, seems unusually sleepy, has unusual breathing, or you have any other concerns about them, talk to your health visitor or doctor as soon as possible.
Cautions with other medicines
Some medicines interfere with the way clonazepam works and increase the chance of you having side effects.
Before you start taking clonazepam, tell a doctor if you're taking:
- anticonvulsants, used to treat epilepsy
- antipsychotics and antidepressants, used to treat mental health problems and depression
- hypnotics, used to treat anxiety or sleep problems
- medicines used to treat muscle spasms, such as baclofen or tizanidine
- medicines used to lower blood pressure including ACE inhibitors such as enalapril and lisionopril; calcium channel blockers such as amlodipine and felodipine; and diuretics such as indapamide and bendroflumethiazide
- drowsy (sedating) antihistamines, such as chlorphenamine or promethazine
- strong painkillers such as codeine, methadone, morphine, oxycodone, pethidine or tramadol.
- cimetidine, a medicine for stomach problems and heartburn
- rifampicin, (to treat bacterial infections) or antifungal medicines such as fluconazole
Mixing clonazepam with herbal remedies or supplements
There's very little information about taking herbal remedies and supplements with clonazepam.
Do not take herbal medicines for anxiety or insomnia, such as valerian or passionflower, with clonazepam. They can increase the drowsy effects of clonazepam and may also have other side effects.
For safety, tell a doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins, or supplements.
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