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Clonazepam Alissa 0.5 mg Tablets Clonazepam Alissa 2 mg Tablets – patient leaflet, side effects, dosage

Last updated: · Text from the MHRA, as of · About this document

Medicine status: Prescription only (POM) Controlled drug (Schedule 4) Details

Medicine strength:
0.5 mg
Other strengths and forms:
Contains active substance:
ATC code:

Patient leaflet - Clonazepam Alissa 0.5 mg tablets

1. What clonazepam tablets are and what they are used for

Clonazepam tablets contain the active substance clonazepam, which belongs to a group of medicines called benzodiazepines.

Clonazepam tablets are used to treat epilepsy in infants, children and adults.

  • They lower the number of fits (seizures) that you have.
  • Any fits that you do have will be less serious.

This medicine has been prescribed to you and should not be given to anyone else.

Benzodiazepines can cause dependence, tolerance and addiction, and you may get withdrawal symptoms if you stop taking it or reduce the dose suddenly. Your prescriber should have explained how long you will be taking it for and, when it is appropriate to stop, how to do this safely. When your treatment is stopped, it is usually done gradually over a period which is specific to you and may occur over a period of weeks to months. If this medicine is being used for the treatment of epilepsy you must continue to take it as prescribed by your doctor.

2. What you need to know before you take clonazepam tablets

Do not take clonazepam tablets if you are allergic (hypersensitive) to:

  • clonazepam or any of the other ingredients of this medicine (listed in section 6).
  • other benzodiazepine medicines, such as diazepam, flurazepam and temazepam.

Do not take clonazepam tablets if any of the above apply to you. If you are not sure, talk to your doctor or pharmacist before taking clonazepam tablets.

Do not take clonazepam tablets if you have:

  • breathing problems or lung disease
  • severe liver problems
  • a condition called ‘sleep apnoea syndrome’ (where your breathing stops when you are asleep)
  • a condition called ‘myasthenia gravis’ (where your muscles become weak and get tired easily)
  • problems with alcohol or drug (prescription or recreational) use

Do not take clonazepam tablets if any of the above apply to you. If you are not sure, talk to your doctor or pharmacist before taking clonazepam tablets.

Warnings and precautions

A small number of people being treated with anti-epileptics such as clonazepam have had thoughts of harming or killing themselves. If at any time you have these thoughts, contact your doctor immediately. Talk to your doctor or pharmacist before taking clonazepam tablets if:

  • you have a lung, liver or kidney problem
  • you have ever had depression
  • you have ever tried to harm or kill yourself
  • a close friend or relative has recently died
  • you are or have ever been addicted to opioids, alcohol, prescription medicines, or illegal drugs, or if you have ever had a history of struggling to control your alcohol or drug intake.
  • you have previously suffered from withdrawal symptoms such as agitation, anxiety, shaking or sweating, when you have stopped taking alcohol or drugs.
  • you feel you need to take more clonazepam tablets to get the same level of symptom control, this may mean you are developing tolerance to the effects of this medicine or are becoming addicted to it. Speak to your prescriber who will discuss your treatment and may change your dose or switch you to an alternative medication.
  • you have spinal or cerebellar ataxia (where you may become shaky and unsteady, have slurred speech or rapid eye movements)
  • you have a rare, inherited blood condition called ‘porphyria’
  • you are elderly or debilitated (weak); your doctor may adjust your dose.

Other medicines and clonazepam tablets

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. This includes medicines obtained without a prescription, including herbal medicines.

This is because clonazepam tablets can affect the way some other medicines work. Also some other medicines can affect the way clonazepam tablets work.

In particular, tell your doctor or pharmacist if you are taking any of the following medicines:

  • other medicines to treat epilepsy, such as carbamazepine, hydantoins, phenobarbital, phenytoin, primidone or sodium valproate

    • cimetidine (used to treat stomach problems and heartburn)
    • rifampicin (an antibiotic used to treat infections)
    • medicines to make you sleep (hypnotics), or that make you feel sleepy as a side-effect
    • medicines that help with anxiety (tranquillisers)
    • pain-killers (analgesics) or medicines to relax your muscles (muscle relaxants)
    • medicines that reduce your blood pressure, such as ramipril, candesartan, amlodipine, doxazosin If any of the above applies to you (or you are not sure), talk to your doctor or pharmacist before taking clonazepam tablets. Concomitant use of clonazepam tablets and opioids (strong pain killers, medicines for substitution therapy and some cough medicines) increases the risk of drowsiness, difficulties in breathing (respiratory depression), coma and may be life-threatening. Because of this, concomitant use should only be considered when other treatment options are not possible. However, if your doctor does prescribe clonazepam tablets together with opioids the dose and duration of concomitant treatment should be limited by your doctor.

Please tell your doctor about all opioid medicines you are taking and follow your doctor’s dose recommendation closely. It could be helpful to inform friends or relatives to be aware of the signs and symptoms stated above. Contact your doctor when experiencing such symptoms.

Operations

If you are going to have an anaesthetic for an operation or for dental treatment, it is important to tell your doctor or dentist that you are taking clonazepam tablets.

Clonazepam tablets and alcohol

Do not drink alcohol while you are taking clonazepam tablets. This is because it may cause side effects or cause your fits to return. Alcohol can also increase the effects of clonazepam tablets, possibly leading to severe sedation that could result in coma or death.

Pregnancy and breast-feeding

If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine. Clonazepam is known to have harmful effects on the unborn child. Driving and using machines

Talk to your doctor about driving and using machines or tools, whilst you are taking clonazepam tablets. This is because it can slow down your reactions, particularly when you start taking it. If you are in any doubt about whether you can do a particular activity, talk to your doctor.

The medicine can affect your ability to drive as it may make you sleepy or dizzy.

  • Do not drive while taking this medicine until you know how it affects you.
  • It is an offence to drive if this medicine affects your ability to drive.
  • However, you would not be committing an offence if:

    • The medicine has been prescribed to treat a medical or dental problem and
    • you have taken it according to the instructions given by the prescriber or in the information provided with the medicine and
    • it was not affecting your ability to drive safely.

Talk to your doctor or pharmacist if you are not sure whether it is safe for you to drive while taking this medicine. Dependence

Taking this medicine regularly, particularly for a long time, can lead to physical dependence and addiction. Your prescriber should have explained how long you will be taking it for and, when it is appropriate to stop, how to do this safely. When your treatment is stopped, it is usually done gradually over a period which is specific to you and may occur over a period of weeks to months.

Physical dependence and addiction can cause withdrawal symptoms when you stop taking this medicine. Withdrawal symptoms can include:

  • Headaches, muscle pain, anxiety, tension, depression, restlessness, sweating, confusion or irritability. Do not stop taking your tablets suddenly.
  • This could lead to more serious symptoms such as loss of the sense of reality, feeling unreal or detached from life, and unable to feel emotion.
  • Some patients have also experienced numbness or tingling of the arms or legs, tinnitus (ringing sounds in the ears), oversensitivity to light, sound and touch, uncontrolled or overactive movements, twitching, shaking, feeling sick, being sick, stomach upsets or stomach pain, loss of appetite, agitation, abnormally fast heartbeats, panic attacks, dizziness or feeling that you are about to fall, memory loss, hallucinations, feeling stiff and unable to move easily, feeling very warm, convulsions (sudden uncontrolled shaking or jerking of the body).

Your prescriber will discuss with you how to gradually reduce your dose before stopping the medicine. It is important that you do not stop taking the medicine suddenly as you will be more likely to experience withdrawal symptoms. Your prescriber will ensure that your plan for stopping treatment is tailored to you and can be adapted according to your needs and experience of any withdrawal symptoms.

Benzodiazepines should only be used by those they are prescribed for. Do not give your medicine to anyone else. Taking higher doses or more frequent doses of benzodiazepines, may increase the risk of addiction. Overuse and misuse can lead to overdose and/or death.

Clonazepam tablets contain lactose

If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.

3. How to take clonazepam tablets

Always take clonazepam tablets exactly as your doctor has told you. Check with your doctor if you are not sure.

  • Swallow the tablets with water. The tablets can be broken in half to give a smaller dose.
  • Your doctor will start you on a low dose and may increase it gradually over 2 to 4 weeks until the right dose has been found for you.
  • Your doctor will usually tell you to split your daily dose into three or four equal amounts which you will take at evenly spaced times throughout the day.
  • If the daily dose cannot be split equally, take the largest dose at bedtime.
  • Once your doctor has found the right dose for you, they may tell you to take your medicine as a single dose in the evening. Adults and children over 12 years

The usual starting dose is 1 mg a day, or less. This will be increased gradually, usually to between 4 mg and 8 mg a day, although your doctor may tell you to take more. The maximum dose is 20 mg a day.

Elderly patients

The usual starting dose is 0.5 mg a day, or less. This will be increased gradually, usually to between 4 mg and 8 mg a day, although your doctor may tell you to take more. The maximum dose is 20 mg a day.

Infants (aged 0 to 1 year)

The usual starting dose is 0.25 mg a day, or less. This will be increased gradually, usually to between 0.5 mg and 1 mg a day.

Continued overleaf Small children (aged 1 to 5 years)

The usual starting dose is 0.25 mg a day, or less. This will be increased gradually, usually to between 1 mg and 3 mg a day. Older children (aged 5 to 12 years)

The usual starting dose is 0.5 mg a day, or less. This will be increased gradually, usually to between 3 mg and 6 mg a day. Your prescriber should have discussed with you how long the course of tablets will last. They will arrange a plan for stopping treatment. This will outline how to gradually reduce the dose and stop taking the medicine. Your prescriber will ensure that your plan for stopping treatment is tailored to you and can be adapted according to your needs and experience of any withdrawal symptoms.

If you take more clonazepam tablets than you should

If you take more clonazepam tablets than you should, talk to a doctor or go to your nearest hospital straight away. Take the medicine pack with you.

If you take too much clonazepam, you may feel drowsy, sleepy, light-headed, have a lack of coordination or be less responsive than normal. If someone else takes your clonazepam tablets by mistake, they should talk to a doctor or go to a hospital straight away.

If you forget to take clonazepam tablets

If you forget to take a dose, skip the missed dose. Then take the next dose when it is due.

Do not take a double dose (two doses at the same time) to make up for a forgotten dose.

If you stop taking clonazepam tablets

Do not suddenly stop taking this medicine. If you want to stop taking this medicine, discuss this with your prescriber first. They will tell you how to do this, usually by reducing the dose gradually so that any unpleasant withdrawal effects are kept to a minimum. This may occur over a period of weeks to months. Your prescriber will ensure that your plan for stopping treatment is tailored to you and can be adapted according to your needs and experience of any withdrawal symptoms. Withdrawal symptoms such as:

  • Headaches, muscle pain, anxiety, tension, depression, restlessness, sweating, confusion or irritability.
  • Do not stop taking your tablets suddenly. This could lead to more serious symptoms such as loss of the sense of reality, feeling unreal or detached from life, and unable to feel emotion.
  • Some patients have also experienced numbness or tingling of the arms or legs, tinnitus (ringing sounds in the ears), oversensitivity to light, sound and touch, uncontrolled or overactive movements, twitching, shaking, feeling sick, being sick, stomach upsets or stomach pain, loss of appetite, agitation, abnormally fast heartbeats, panic attacks, dizziness or feeling that you are about to fall, memory loss, hallucinations, feeling stiff and unable to move easily, feeling very warm, convulsions (sudden uncontrolled shaking or jerking of the body).

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, clonazepam tablets can cause side effects, although not everybody gets them. Important side effects to look out for:

Allergic reactions

If you get an allergic reaction, see a doctor straight away.

The signs may include:

  • sudden swelling of the throat, face, lips and mouth.

    This may make it difficult to breathe or swallow

  • sudden swelling of the hands, feet and ankles
  • skin rash or itching

Effects on the heart

If you notice any of the following effects, see a doctor straight away.

The signs may include:

  • breathlessness, swelling of the ankles, cough, tiredness and a racing heart
  • chest pain which may spread to your neck and shoulders and down your left arm

Effects on behaviour

If you notice any of the following effects, talk to your doctor as they may want you to stop taking clonazepam tablets. The signs may include:

  • being aggressive, hyperactive, irritable, nervous, agitated, hostile or anxious
  • problems sleeping, nightmares and abnormal dreams
  • mental problems such as seeing or hearing things that are not really there (hallucinations), delusions (believing in things that are not real) and problems with your speech
  • inappropriate behaviour, emotional and mood changes
  • types of fits (seizures) that you have not had before.

Infants and children

  • If an infant or small child is taking clonazepam tablets, watch them carefully. This is because they could develop breathing problems, coughing or choking. This can be caused by too much saliva being made.
  • Early puberty in children. This is reversible after stopping treatment with clonazepam.

Other possible side effects

When you start taking clonazepam tablets you may notice the following effects:

  • feeling drowsy and tired
  • feeling dizzy and light-headed
  • weak or floppy muscles or jerky movements (poor coordination)
  • feeling unsteady when walking

If you notice any of these effects, talk to your doctor.

Your doctor may be able to help you by giving you a lower dose of clonazepam and then increasing it slowly. The following may occur at any time during your treatment:

Mind and nervous system

  • poor concentration, confusion and a feeling of being lost (disorientation)
  • feeling restless
  • difficulty remembering new things
  • headache
  • depression
  • slowing or slurring of speech
  • poor co-ordination, including feeling unsteady when walking
  • an increase in how often you have fits.

Liver, kidney and blood

  • changes in how well your liver is working (shown by blood tests)
  • loss of bladder control

    • blood problems. The signs include feeling tired, bruising easily, being short of breath and nose bleeds. Your doctor may want you to have blood tests from time to time.

Stomach and gut

  • feeling sick (nausea)
  • stomach upset.

Eyes

  • double vision
  • jerky movements of the eyes (nystagmus)

Breathing

  • breathing problems (respiratory depression). Early signs include suddenly noisy, difficult and uneven breathing. Your skin may become blue.

Skin and hair

  • skin rashes, hives (lumpy rash) and itchy skin
  • changes to the colour of your skin
  • hair loss (the hair usually grows back)

Sexual

  • loss of sex drive
  • difficulty getting or keeping an erection (erectile dysfunction)

Unknown frequency: dependence and addiction (see section “How do I know if I am tolerant or addicted?”). Drug Withdrawal symptoms

When you stop taking Lorazepam tablets, you may experience drug withdrawal symptoms, which include:

  • Headaches, muscle pain, anxiety, tension, depression, restlessness, sweating, confusion or irritability.
  • Do not stop taking your tablets suddenly. This could lead to more serious symptoms such as loss of the sense of reality, feeling unreal or detached from life, and unable to feel emotion.
  • Some patients have also experienced numbness or tingling of the arms or legs, tinnitus (ringing sounds in the ears), oversensitivity to light, sound and touch, uncontrolled or overactive movements, twitching, shaking, feeling sick, being sick, stomach upsets or stomach pain, loss of appetite, agitation, abnormally fast heartbeats, panic attacks, dizziness or feeling that you are about to fall, memory loss, hallucinations, feeling stiff and unable to move easily, feeling very warm, convulsions (sudden uncontrolled shaking or jerking of the body). How do I know if I am tolerant or addicted?

If you notice any of the following signs whilst taking Lorazepam tablets it could be a sign that you have become addicted.

  • You may feel the need to keep taking the medication for longer than your doctor recommended
  • You feel you need to use more than the recommended dose
  • You are using the medicine for reasons other than prescribed
  • When you stop taking the medicine you feel unwell, and you feel better once taking the medicine again If you notice any of these signs, it is important you talk to your prescriber.

Injury

  • Patients taking benzodiazepine medicines are at risk of falling and breaking bones. The risk is increased in the elderly and those taking other sedatives (including alcohol).

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme. Website: www.mhra. gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store clonazepam tablets

Keep this medicine out of the sight and reach of children.

Store below 25ºC. Keep the blisters in the outer carton to protect from light.

Do not use this medicine after the expiry date (EXP) which is stated on the carton and blister. Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment. Only keep the tablets if your doctor tells you to.

6. Contents of the pack and other information

What clonazepam tablets contain

The active substance in clonazepam tablets is clonazepam.

Clonazepam Alissa 0.5 mg Tablets

Each tablet contains 0.5 mg clonazepam.

Clonazepam Alissa 2 mg Tablets

Each tablet contains 2 mg clonazepam.

The other ingredients are:

lactose monohydrate,

cellulose microcrystalline type 102,

starch, pregelatinized (maize),

magnesium stearate.

What clonazepam tablets look like and contents of the pack

Clonazepam Alissa 0.5 mg Tablets

White or almost white tablets, oblong, flat, with a score line on one side. The size is 9 mm x 4.5 mm. The tablets can be divided into equal halves.

Clonazepam Alissa 2 mg Tablets

White or almost white tablets, round, flat, cross-scored on one side. The diameter is 7 mm. The tablets can be divided into equal halves or quarters.

Packing: 14, 20, 30, 50, 60 or 100 tablets in the carton box. Not all pack sizes may be marketed. Marketing Authorisation Holder

Alissa Healthcare Research Ltd, Unit 5, Fulcrum 1, Solent Way, Whiteley, Fareham, Hampshire, PO15 7FE, United Kingdom

Manufacturer

Tarchominskie Zaklady Farmaceutyczne Polfa S.A., UI. Aleksandra Fleminga 2, Warsaw, Mazowieckie, 03-176, Poland

This leaflet was last revised in: March 2026 P00007/02

Clonazepam PIL
P00007 V6 06/03/2026
Zurich Condensed 9pt

Size 320 x 320mm

About this document

Source: MHRA - Medicines and Healthcare products Regulatory Agency (products.mhra.gov.uk) · Marketing authorisation: PL 30322/0057

Last revision stated in the text: March 2026 · MHRA data as of 13 October 2026

Found a mistake? Tell us on the contact page.

The information on this site does not replace the advice of a doctor or pharmacist.

Facts about Clonazepam Alissa 0.5 mg tablets

Prescription needed? Yes, prescription-only medicine (POM)
Controlled drug
Yes, Schedule 4 of the Misuse of Drugs Regulations?
  • Controlled drugs are medicines that UK law controls more strictly because they can be misused or cause dependence. The Misuse of Drugs Regulations 2001 divide them into 5 schedules: schedule 1 has the strictest rules, schedule 5 the lightest.
  • Schedule 4 has lighter rules. Its part I covers benzodiazepines and similar sleeping tablets, for example diazepam or zopiclone.
  • A prescription is valid for 28 days and usually covers up to 30 days of treatment.
  • Travelling abroad: you can usually carry up to 3 months' supply. Take your prescription or a letter from your doctor to show it is yours, and check the rules of the country you are going to (GOV.UK).
  • Never give it to anyone else.
Active substance Clonazepam
Strength 0.5 mg
Pharmaceutical form Oral tablet
White or almost white tablets, oblong, flat, with a score line on one side. The size is 9 mm x 4.5 mm.
The tablets can be divided into equal halves.
How is it taken Oral
Excipients Lactose monohydrate, Cellulose microcrystalline type 102, Starch, pregelatinized (maize), Magnesium stearate
Pack sizes 100 tablet
Is it available? Listed as available (NHS Dictionary of Medicines and Devices – not a record of current supplies)
Shelf life 24 months
Storage Store below 25°C. Keep the blisters in the outer carton to protect from light.
Drug group (ATC) Antiepileptics, Benzodiazepine derivatives
  1. N Nervous system drugs
    1. N03 Antiepileptics
      1. N03A Antiepileptics
        1. N03AE Benzodiazepine derivative antiepileptics
          1. N03AE01 clonazepam
Marketing authorisation PL 30322/0057 (first authorised 1 March 2024)
Marketing authorisation holder Alissa Healthcare Research Ltd
Codes GTIN 5060135171933 · BNF 04080100

Sources: the MHRA product information (products.mhra.gov.uk) and the NHS Dictionary of Medicines and Devices (dm+d), release 10.2.0 of 19 October 2026, NHS Business Services Authority. Contains public sector information licensed under the Open Government Licence v3.0.