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Phenobarbital Accord 15 mg tablet – patient leaflet, side effects, dosage

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Key facts
Status:
Prescription only (POM) Controlled drug (Schedule 3)
Medicine strength:
15 mg
Other strengths and forms:
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Patient leaflet - Phenobarbital Accord 15 mg tablet

1 What Phenobarbital Tablets are and what they are used for

Phenobarbital Tablets belong to a group of medicines called barbiturates. These medicines reduce brain activity which would otherwise cause fits or seizures in epilepsy, except absence seizures (day dreaming).

2 What you need to know before you take Phenobarbital Tablets

Do not take Phenobarbital Tablets if you:

  • are allergic to phenobarbital, other barbiturates or any of the other ingredients of this medicine (listed in section 6)
  • have porphyria (a genetic or inherited disorder of the red blood pigment haemoglobin)
  • have severe breathing difficulties
  • have severe kidney or liver disease.

If you develop a rash or the following skin symptoms, seek immediate advice from a doctor and tell them that you are taking this medicine:

  • potentially life-threatening skin rashes (Stevens-Johnson syndrome, toxic epidermal necrolysis) have been reported with the use of Phenobarbital Tablets appearing initially as reddish target-like spots or circular patches often with central blisters on the trunk. Additional signs to look for include ulcers in the mouth, throat, nose or genitals and conjunctivitis (red and swollen eyes). These potentially life-threatening skin rashes are often accompanied by flu-like symptoms. The rash may progress to widespread blistering or peeling of the skin. The highest risk for occurrence of serious skin reactions is within the first weeks of treatment.
  • If you have developed Stevens-Johnson syndrome or toxic epidermal necrolysis with the use of Phenobarbital Tablets you must not be re-started on Phenobarbital Tablets at any time. Warnings and precautions

Talk to your doctor or pharmacist before taking Phenobarbital Tablets if you:

  • or the person taking these tablets are young, run down, senile or have a history of drug abuse or alcoholism

  • Muscle, bone and connective tissue: Problems with inflammation of tendons (e.g. Dupuytren’s contracture of the hand, frozen shoulder), joint pain (arthralgia), bone softening and bone disease. There have been reports of bone disorders including osteopenia and osteoporosis (thinning of the bone) and fractures. Check with your doctor or pharmacist if you are on long-term antiepileptic medication, have a history of osteoporosis, or take steroids.
  • Reproductive system: Scar tissue formation in the penis that can cause various penis problems (Peyronie’s disease of the penis).
  • Mental health: Restlessness and confusion in the elderly, unusual excitement, depression, memory impairment, hallucinations.
  • Nervous system: Hyperactivity, behavioural disturbances in children, jerky movements, jerky eye movements, drowsiness, lethargy.
  • Heart: Low blood pressure.
  • Lungs: Difficulty breathing.
  • Liver: Inflammation of the liver (hepatitis), damaged bile system (cholestasis) - seen as yellowing of skin and whites of eyes.
  • Kidneys: Changes in the amount or need to pass water.
  • Skin: Rashes, erythema multiforme (circular, irregular red patches), lumps in the armpits or groin area. Potentially life-threatening skin rashes (Stevens-Johnson syndrome - severe skin rash with flushing, fever, blisters or ulcers and toxic epidermal necrolysis - severe rash involving reddening, peeling and swelling of the skin that resembles severe burns) have been reported very rarely (see section 2).

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 at: 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.

3 How to take Phenobarbital Tablets

Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.

You are advised not to drink alcohol, check with your doctor if you have any questions.

Swallow the tablets with water at the same time each day.

Doses:

  • Adults: 60mg-180mg at night.
  • Children: 5mg-8mg per kg of bodyweight a day.

  • Elderly: your doctor may prescribe a lower dose. If you take more Phenobarbital Tablets than you should

If you (or someone else) swallow a lot of tablets at the same time, or you think a child may have swallowed any, contact your nearest hospital casualty department or tell your doctor immediately.

Signs of an overdose include drowsiness, speech problems, jerky movements, jerky eye movements, loss of inhibition, reduced reflex response, low body temperature, low blood pressure and breathing problems.

If you forget to take Phenobarbital Tablets

Do not take a double dose to make up for a forgotten dose. If you forget to take a dose, take it as soon as you remember it and then take the next dose at the right time.

If you stop taking Phenobarbital Tablets

If you stop taking the tablets you may develop withdrawal effects such as sleeplessness, anxiety, tremor, dizziness, feeling sick, fits and delirium.

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

4 Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

Tell your doctor if you notice any of the following side effects or notice any other effects not listed:

  • Allergic reaction: Skin rash, fever, swelling of the face, lips, tongue or throat, or difficulty breathing or swallowing.
  • Blood: Altered numbers and types of blood cells, if you notice increased bruising, nosebleeds, sore throats or infections, you should tell your doctor who may want to perform a blood test.

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5 How to store Phenobarbital Tablets

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

Store below 25°C. Keep the blister in the outer carton in order to protect from light.

Do not take this medicine after the expiry date which is stated on the carton. The expiry date refers to the last day of that month.

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.

6 Contents of the pack and other information

What Phenobarbital Tablets contain

  • The active substance (the ingredient that makes the tablet work) is phenobarbital. Each tablet contains 15mg of the active substance.
  • The other ingredients are lactose, starch, talc and stearic acid.

What Phenobarbital Tablets look like and contents of the pack

Phenobarbital 15mg Tablets are white circular tablets with flat bevelled edge, impressed “PN” on one face and “C” on the reverse. Nominal diameter 5.0mm. Pack size is 28.

Marketing Authorisation Holder

Accord Healthcare Limited

Sage House, 319 Pinner Road

North Harrow, Middlesex

HA1 4HF, United Kingdom

Manufacturer

Accord, Barnstaple, EX32 8NS, UK

This leaflet was last revised in June 2023.

If you would like a leaflet with larger text, please contact 01271 385257

51020677 BBBB7362

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Technologist:

Technically Approved

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  • have kidney or liver problems
  • have breathing difficulties
  • have severe or long term pain.

A small number of people being treated with anti-epileptics such as phenobarbital have had thoughts of harming or killing themselves. If at any time you have these thoughts, immediately contact your doctor. Other medicines and Phenobarbital Tablets

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines, especially:

  • disopyramide and quinidine (to treat irregular heartbeats)
  • chloramphenicol, doxycycline, metronidazole, rifampicin, telithromycin, griseofluvin, itraconazole, posaconazole, voriconazole, abacavir, amprenavir, lopinavir, indinavir, darunavir, nelfinavir and saquinavir (to treat infections)
  • medicines used to thin the blood such as warfarin
  • mianserin, paroxetine, MAOI or tricyclic antidepressants or St John’s wort (Hypericum perforatum) a herbal remedy (to treat depression)
  • oxcarbazepine, primidone, phenytoin, sodium valproate, carbamazepine, lamotrigine, tiagabine, zonisamide, ethosuxamide and vigabatrin (to treat epilepsy)
  • chlorpromazine, thioridazine, haloperidol, aripiprazole and clonazepam (to treat mental illness)
  • felodipine, verapamil, diltiazem, nimodipine, nifedipine, metoprolol, timolol and propranolol (to treat high blood pressure)
  • digitoxin or eplerenone (to treat certain heart conditions)
  • ciclosporin or tacrolimus (to prevent organ transplant rejection)
  • steroids such as hydrocortisone or prednisolone
  • folic acid or vitamin D (supplements)
  • toremifene, gestrinone, irinotecan or etoposide (to treat some cancers)
  • methadone (used in severe pain or drug addiction)
  • oral contraceptives (talk to your doctor about the best method of contraception for you) or tibolone (female hormone)
  • levothyroxine (thyroid hormone)
  • montelukast or theophylline (to treat asthma)
  • tropisetron and aprepitant (to treat nausea and vomiting)
  • memantine (to treat dementia)
  • methylphenidate (to treat attention deficit disorder)
  • sodium oxybate (to treat narcolepsy).

    Pregnancy, contraception in women, breast-feeding

    Pregnancy

    What you should know about the use of antiepileptic drugs in pregnancy

    If you are pregnant, or think you may be pregnant, you must tell your doctor straight away and discuss possible risks the epilepsy medicine you are taking might pose to your unborn baby. If you are planning to become pregnant you should discuss your epilepsy treatment with your doctor as early as possible before you become pregnant. You should not stop your treatment without discussing this with your doctor. Suddenly stopping may lead to breakthrough seizures which may harm you and your unborn baby. It is important that your epilepsy is well controlled.

    Taking phenobarbital during pregnancy increases the chance that the baby may have a physical birth abnormality. Studies with women treated with phenobarbital for epilepsy have shown that around 6-7 babies in every 100 will have serious physical birth abnormalities. This compares to 2-3 babies in every 100 born to women who don’t have epilepsy. The most common types of serious physical birth abnormalities (major congenital malformations) reported for phenobarbital include heart defects and, less commonly, cleft lip and palate defects.

    Studies have found that the risk of physical birth abnormalities increases with increasing dose of phenobarbital. Therefore, your doctor will prescribe you the lowest effective dose. Taking more than one epilepsy medicine at the same time may also increase the risk of physical birth abnormalities. Where possible, your doctor will consider using one epilepsy medicine only to control your epilepsy.

    Phenobarbital should not be used during pregnancy unless nothing else works for you.

    Talk to your doctor immediately if you are pregnant. Your doctor should discuss the possible effects of phenobarbital tablets on the unborn child and the risks and benefits of treatment should be considered carefully. Do not stop taking phenobarbital until you have discussed this with your doctor, as stopping the medication abruptly may increase the risk of developing seizures, which may have harmful effects on you and the unborn child.

    If you have taken phenobarbital during the last third of the pregnancy, appropriate monitoring should be

    conducted to detect potential disorders in the newborn, such as seizures, excessive crying, muscle weakness, sucking disorders

    Your doctor may advise you to take folic acid if you’re planning to become pregnant and while you’re pregnant. Your doctor may adjust your phenobarbital dose when you take folic acid. This is because folic acid supplements may affect your blood levels of phenobarbital. Some studies observed that taking phenobarbital during pregnancy increases the chance that the baby may have problems affecting learning and thinking abilities. Studies have also shown that babies born to mothers who have taken phenobarbital are born of smaller size than expected compared to children of mothers who did not take phenobarbital.

    Women of child-bearing potential/ Contraception

    If you are a woman of childbearing age you should use effective contraception during treatment with phenobarbital and for two months after treatment. Phenobarbital may affect how hormonal contraceptives, such as the contraceptive pill, work and make them less effective at preventing pregnancy. Talk to your doctor, who will discuss with you the most suitable type of contraception to use while you are taking phenobarbital. If you are a woman of childbearing age and are planning a pregnancy, talk to your doctor before you stop contraception and before you become pregnant about switching to other suitable treatments in order to avoid exposing the unborn baby to phenobarbital. Breast-feeding

    If you are taking Phenobarbital Tablets, do not breast-feed, as the medicine will pass into the breast milk and may harm the baby.

    Driving and using machines

    Phenobarbital Tablets may make you feel less alert than normal. Make sure you are not affected before driving or operating machinery.

    Phenobarbital 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 medicinal product.

    Tests

    If you see another doctor or go into hospital or need a blood or urine test, let them know what medicines you are taking as Phenobarbital Tablets may interfere with the results.

About this document

Source: MHRA - Medicines and Healthcare products Regulatory Agency (products.mhra.gov.uk) · Marketing authorisation: PL 20075/0703

Last revision stated in the text: June 2023 · MHRA data as of 13 October 2026

What the sections and the side effect frequencies mean: How to read a patient leaflet

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 Phenobarbital Accord 15 mg tablet

What these facts mean

Prescription needed?? Yes, prescription-only medicine (POM)
Controlled drug?
Yes, Schedule 3 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 and schedule 5 the least strict.
  • Schedule 3 includes, for example, tramadol, gabapentin, pregabalin and buprenorphine.
  • A prescription is valid for 28 days and usually covers up to 30 days of treatment. In England it cannot be issued as a repeat dispensing prescription.
  • Travelling abroad: carry it in your hand luggage, 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 with its embassy before you travel (GOV.UK).
Active substance? Phenobarbital
Strength? 15 mg
Pharmaceutical form? Oral tablet
White circular tablets with flat bevelled edge, impressed “PN” on one face and “C” on the reverse. Nominal diameter 5.0 mm.
How is it taken? Oral
Excipients? Lactose BP, Starch BP, Talc BP, Stearic Acid BP.
Pack sizes 28 tablet
Is it available?? Listed as available (NHS Dictionary of Medicines and Devices – not a record of current supplies)
Shelf life? 18 months.
Storage Store below 25°C. Keep the blister in the outer carton in order to protect from light.
Drug group (ATC)?
  1. N Nervous system drugs
    1. N03 Antiepileptics
      1. N03A Antiepileptics
        1. N03AA Barbiturates and derivatives
          1. N03AA02 phenobarbital
Marketing authorisation? PL 20075/0703
Marketing authorisation holder? Accord Healthcare Limited
Codes? GTIN 5055565738610 · BNF 04080100

Sources: the MHRA product information (products.mhra.gov.uk) and the NHS Dictionary of Medicines and Devices (dm+d), release 11.1.0 of 9 November 2026, NHS Business Services Authority. Contains public sector information licensed under the Open Government Licence v3.0.