Perphenazine tablets (Fentazin)

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Perphenazine is prescribed for a number of different problems. Ask your doctor if you are unsure why it has been prescribed for you.

It may slow your reactions and make you feel drowsy. If this happens, do not drive or use tools or machines.

Keep your regular appointments with your doctor. This is so your progress can be checked.

Type of medicineA phenothiazine antipsychotic medicine
Used forEasing the symptoms of schizophrenia and other mental, emotional or behavioural problems; the treatment of severe nausea and vomiting
Also calledFentazin®
Available asTablets

Perphenazine is used to relieve the symptoms of schizophrenia and other problems which affect the way you think, feel or behave. These problems may make you hear, see or sense things that are not there, or believe things that are not true, or feel unusually suspicious. Taking perphenazine will help to get these types of symptoms under control. It is occasionally prescribed (for short periods of time only) to people who have become severely agitated or restless.

Perphenazine is also prescribed for people with sickness associated with advanced or terminal illnesses. This is beacuse it has an action on an area in the brain which is in part responsible for controlling vomiting.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking perphenazine it is important that your doctor knows:

  • If you are pregnant or breast-feeding.
  • If you have a heart condition or blood vessel disease.
  • If you have liver, kidney, or prostate problems.
  • If you have breathing problems.
  • If you have an underactive thyroid gland.
  • If you have any of the following: epilepsy, Parkinson's disease, depression, glaucoma (raised pressure in your eye), or myasthenia gravis (a condition which causes muscle weakness).
  • If you have ever had jaundice (yellowing of the skin or the whites of the eyes) or a blood disorder.
  • If you have a tumour on your adrenal gland, a condition called phaeochromocytoma.
  • If you have ever had an allergic reaction to a medicine.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The manufacturer's leaflet will give you more information about perphenazine and a full list of the side-effects which you may experience from taking it.
  • Take perphenazine exactly as your doctor tells you to. As a guide, the usual starting dose for an adult is 4 mg three times a day. Your dose will be less than this if you are elderly (usually, 1-2 mg three times daily). After a short while your doctor may adjust your dose to suit your symptoms. Perphenazine is not suitable for children.
  • You can take perphenazine before or after meals. Swallow the tablet with a drink of water.
  • Try to take your doses at the same times of day each day, as this will help you to remember to take perphenazine regularly.
  • If you forget to take a dose, take it as soon as you remember unless your next dose is due. If your next dose is due, then take the dose which is due but leave out the forgotten one. Do not take two doses together to make up for a missed dose.
  • Your treatment will require careful monitoring to make sure that you get the best possible benefit from perphenazine. Keep your regular doctor's appointments so your progress can be checked. You will need to have some blood tests from time to time.
  • Treatment for schizophrenia is usually long-term. Keep taking perphenazine tablets until your doctor tells you otherwise. Stopping suddenly can cause problems and your doctor may want you to reduce your dose gradually if a change in your treatment becomes necessary. If you have been given perphenazine to relieve severe agitation or anxiety, it will be given to you for a short time only until your symptoms have eased.
  • Perphenazine may cause your skin to become more sensitive to sunlight than normal. Use a sunscreen that protects against UVA light and has a sun protection factor (SPF) of at least 15, especially in strong sunlight or until you know how your skin reacts. Do not use sunbeds.
  • If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking. This is important because perphenazine may interfere with any anaesthetic you receive.
  • If you buy or take any 'over-the-counter' medicines, check with a pharmacist that they are suitable to take with perphenazine. Antacid remedies should not be taken at the same time, as they reduce the amount of perphenazine absorbed by your body.
  • If you drink alcohol, ask your doctor for advice about drinking while you are on perphenazine. Alcohol will increase the chance that you experience side-effects and is unlikely to be recommended for you.
  • If you have diabetes check your blood glucose levels regularly, as perphenazine may affect the levels of sugar in your blood.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with perphenazine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common perphenazine side-effectsWhat can I do if I experience this?
Feeling dizzy or sleepy, blurred vision, slowed reaction timeIf this happens, do not drive or use tools or machines. Do not drink alcohol
HeadacheAsk your doctor or pharmacist to recommend a suitable painkiller
Feeling shaky or restless, unusual or uncontrollable muscle movementsSpeak with your doctor as soon as possible about any of these. Your treatment may need adjusting
Dry mouthTry chewing sugar-free gum or sugar-free sweets
Changes in the way your body regulates temperatureTake care in hot or cold weather to make sure that you don't get too hot or too cold
Feeling light-headed when you stand upThis can happen particularly when you first start taking this medicine. Get up more slowly until you are aware how you react
Changes in weight, difficulty sleeping, mood changes, stuffy nose, changes in sexual ability, breast enlargement, production of breast milk, menstrual problems, fast heartbeats, constipation, difficulty passing urineDiscuss these with your doctor if any become troublesome

Important: if you experience symptoms such as muscle stiffness, a very high temperature, confusion, a fast heartbeat, and sweating you must contact your doctor immediately. These may be signs of a rare but serious condition known as neuroleptic malignant syndrome.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • Manufacturer's PIL, Fentazin® 2 mg and 4 mg tablets; Amdipharm Mercury Company Limited, The electronic Medicines Compendium. Dated January 2013.
  • British National Formulary; 66th Edition (September 2013) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
1457 (v24)
Last Checked:
Next Review:
The Information Standard - certified member

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