Patient leaflet - Cimetidine 800 mg film-coated tablets
1. What Cimetidine is and what it is used for
The name of your medicine is Cimetidine 200 mg film-coated tablets, Cimetidine 400 mg film-coated tablets or Cimetidine 800 mg film-coated tablets (all called Cimetidine in this leaflet). Cimetidine belongs to a group of medicines called “H2 antagonists”.
Cimetidine works by lowering the amount of acid in your stomach. It can be used for the following:
- To treat or prevent ulcers in your stomach and duodenum (the part of the gut the stomach empties into)
- An inflamed food pipe (oesophagitis) where stomach acid has travelled up into your food pipe (acid reflux disease)
- To prevent ulcers from bleeding in seriously ill people
- The management of Zollinger-Ellison Syndrome. This is a problem with your pancreas where too much acid in the stomach can cause ulcers in your stomach, duodenum, gut and food pipe
- The management of short bowel syndrome. This is where some parts of your bowel either do not work or have been removed
- If your pancreas does not work and you are taking enzyme supplements to help you digest your food
- For people at risk of breathing in acid from their stomach (aspiration). This might happen during an operation with a general anaesthetic or in women during labour.
2. What you need to know before you take Cimetidine
Do not take Cimetidine if:
- You are allergic (hypersensitive) to Cimetidine or any of the other ingredients of this medicine listed in Section 6.
Do not take Cimetidine if the above applies to you. If you are not sure, talk to your doctor or pharmacist before taking Cimetidine.
Warnings and precautions
Check with your doctor, pharmacist or nurse before taking your medicine if any of the following apply to you. You may need to be given a different dose or a different medicine.
- You have a blood problem
- You have a kidney problem
- You have ever had a stomach or duodenal ulcer before, particularly if you are also taking a non-steroidal anti-inflammatory drug (NSAID) such as ibuprofen or aspirin
- You are pregnant, might become pregnant or are breast-feeding.
If any of the above apply to you (or you are not sure), talk to your doctor, pharmacist or nurse before taking Cimetidine. You may need to be given a different dose or a different medicine.
Stomach cancer
Cimetidine may hide the signs of stomach cancer. This is more likely to happen if you are middle-aged or elderly or when the cancer is very new. Your doctor will check to make sure that you do not have stomach cancer before you start taking your tablets.
Other medicines and Cimetidine
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 and herbal medicines. This is because Cimetidine can affect the way some other medicines work. Also some other medicines can affect the way Cimetidine works. In particular, tell your doctor or pharmacist if you are taking medicines which:
- Control epilepsy (e.g. phenytoin). Your doctor will monitor you
- Thin the blood (e.g. warfarin). Your doctor will monitor you
- Treat breathing problems (e.g. theophylline)
- May cause your blood cell count to change (e.g. antibiotics)
- Treat fungal (yeast) infections (e.g. ketoconazole, itraconazole, posaconazole)
- Treat diabetes (e.g. glipizide, metformin)
- Treat anxiety (e.g.diazepam)
- Treat depression, called tricyclic antidepressants (e.g. amitriptylline)
- Lower blood pressure or treat heart conditions (e.g. metoprolol, propranolol, nifedipine, diltiazem, procainamide)
- Numb the body such as anaesthetics used in hospital (e.g. lidocaine)
- Are strong pain relievers (e.g.morphine)
- Suppress the immune system (e.g. ciclosporin, tacrolimus)
- Treat HIV/AIDS (e.g. atazanavir)
- Treat tumors or cancer (e.g. carmustine, fluorouracil, epirubicin), or if you are having radiation therapy.
Pregnancy and breast-feeding
If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
Driving and using machines
You may feel dizzy, see or hear things that are not there while taking this medicine. If this happens, do not drive or use any tools or machines.
If any of the above apply to you (or you are not sure), talk to your doctor or pharmacist before taking Cimetidine.
Cimetidine contains sodium
This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially 'sodium-free'
3. How to take Cimetidine
Always take Cimetidine exactly as your doctor has told you. The pharmacist’s label should tell you how much to take and how often. You should check with your doctor or pharmacist if you are not sure.
Taking this medicine
- Swallow the tablets whole with a drink of water
- Do not crush, chew or break them in half
- You will usually take your tablets for at least 4 weeks, but it could be 8 weeks or longer for some problems
- Your doctor may reduce your dose when you start to feel better
- You may take less of this medicine if you have kidney problems or are an older person
- Keep taking these tablets until the course is finished. Keep taking them, even if you feel better. If you stop taking the tablets too soon, your original problem may come back.
How much to take – adults and older people
Depending on what you are taking Cimetidine for, there are different doses. The most you can take in a day is 2400mg, if your doctor tells you to. The usual doses are listed below:
To treat ulcers
- 800mg once each day or 200mg four times each day. If you need more your doctor may prescribe up to 400mg four times each day.
To prevent ulcers
- 400mg once or twice each day.
Inflamed food pipe
- 400mg four times each day
To prevent ulcers from bleeding in seriously ill people
- 200mg to 400mg every four to six hours
Zollinger-Ellison Syndrome
- 400mg four times each day or occasionally your doctor may prescribe more.
Short bowel syndrome
400mg twice each day
With pancreas enzyme supplements
- Four 200mg or 400mg tablets each day (1 to one and a half hours before any meals).
During an operation – to stop you breathing in acid from your stomach
- 400mg one and a half to 2 hours before your operation
- Then 400mg every 4 hours that you are in surgery, if required.
During labour – to stop you breathing in acid from your stomach
- 400mg when you start labour
- Then 400mg every 4 hours that you are in labour, if required.
How much to take – children (give only if your doctor tells you to)
The total amount will be worked out by your doctor as it will depend on how much your child weighs. They will tell you how to split this up and take it through the day.
Children 1 year old and older
- 25 to 30mg each day for each kilogram (kg) of bodyweight
Infants under 1 year old
- 20mg each day for each kilogram (kg) of bodyweight
If you take more Cimetidine than you should
If you take more Cimetidine than you should, talk to a doctor or go to a hospital straight away. Take the medicine pack with you.
If you forget to take Cimetidine
- If you forget to take a tablet, miss out that tablet completely
- Take your next tablet at the normal time
- Do not take a double dose to make up for a forgotten dose.
If you have any further questions on the use of this product, ask your doctor or pharmacist.
4. Possible side effects
Like all medicines, this medicine can have side effects, although not everybody gets them. The following side effects may happen with this medicine:
See a doctor straight away, if you notice any of the following serious side effects:
- Allergic reactions – the signs include a skin rash, itching, swollen or lumpy skin, you have difficulty breathing, have a fever or feel faint
- You have yellow skin or eyes or flu-like symptoms. These could be signs of a liver problem
- You have severe abdominal pains. This could be a sign of inflammation of the pancreas (pancreatitis)
- You have severe pain in your lower back, have cloudy or bloody water (urine). These could be signs of a kidney problem
- You notice that you bruise more easily or have more nose bleeds than usual. You may also get more infections than usual such as a sore throat, look pale or feel generally unwell. These could be signs of changes in your blood cells.
- You develop a slow, fast or uneven heartbeat
- Inflammation of blood vessels caused by an allergic reaction to Cimetidine(hypersensitivity vasculitis). Please tell your doctor if you get any of the following and they get troublesome or last for longer than a few days
Common (affects less than 1 in 10 people)
- Headache
- You feel dizzy or get a rash
- Diarrhoea
- Aching muscles
- You feel tired.
Uncommon (affects less than 1 in 100 people)
- Inability to get or keep an erection (impotence)
- Men getting swollen or tender breasts
- You feel depressed, confused or see or hear things that are not there (hallucinations). Very Rare (affects up to 1 in 10,000 people)
- Unexpected secretion of breast milk in men or women
- Aching joints
- Fever
- Hair loss.
If you notice any side effects not listed in this leaflet, please tell your doctor or pharmacist.
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 Cimetidine
- Keep out of the sight and reach of children
- Do not use the tablets after the expiry date which is stated on the carton and blister strip after EXP. The expiry date refers to the last day of that month
- Do not store above 25°C. Store in the original packaging
- Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.
6. Contents of the pack and other information
What Cimetidine contains
- The active substance is cimetidine. The tablets come in three strengths containing 200mg, 400mg or 800mg cimetidine
- The other ingredients are microcrystalline cellulose, povidone K30, sodium starch glycollate, sodium lauryl sulfate, colloidal anhydrous silica, magnesium stearate hypromellose (E464), titanium dioxide (E171), macrogol 400, indigo carmine aluminium lake (E132), iron oxide yellow (E172), quinoline yellow aluminium lake (E104).
What Cimetidine looks like and contents of the pack
The tablets are film-coated and pale green in colour.
- The 200mg tablets are circular in shape with CIM200 written on one side
- The 400mg tablets oval biconvex in shape with CIM400 written on one side
- The 800mg tablets are oval in shape with CIM800 written on one side
Cimetidine is only available from your pharmacist on prescription in pack sizes of 60s (200mg and 400mg) and 30s (800mg).
MA Holder:
Steranco Healthcare UK Ltd.
John Eccles House, Robert Robinson Avenue,
Oxford Science Park, Oxford, Oxfordshire
OX4 4GP, UK
Manufacturer:
Medley Pharma Limited.
Unit 2A, Olympic Way, Sefton Business Park,
Bootle, Merseyside, L30 1RD, UK
Other sources of information
To request a copy of this leaflet in braille, please email medinfo@steranco.co.uk
Date of last revision: August 2026