Cimetidine tablets BP 800 mg – patient leaflet, side effects, dosage

1. WHAT CIMETIDINE TABLETS ARE AND WHAT ARE THEY USED FOR

Cimetidine Tablets belong to a group of medicines called H2-receptor antagonists which act to decrease the natural production of acid in the stomach.

Cimetidine Tablets have been prescribed to treat any of the following:

! Ulcers in the stomach (gastric ulcer) or in the upper part

of the intestine (duodenum ulcer)

! Acid from the stomach escaping into the food pipe

causing pain, inflammation and heartburn (oesophageal reflux disease)

! Excess acid in the stomach caused by a tumor in the

pancreas (Zollinger-Ellison syndrome)

! Ulcers in the stomach or duodenum which may be caused

by non-steroidal anti-inflammatory drugs (NSAIDS), often used to reduce pain, fever and inflammation ! Various conditions where reduction of gastric acid by

cimetidine has been shown to be beneficial e.g. ! Indigestion symptoms (e.g. stomach pain or discomfort,

heartburn)

! Meal-related upper abdominal pain

! To prevent stress ulcers from bleeding

! To be given before general anaesthesia to prevent

damage to the lungs caused by breathing in stomach fluids (acid aspiration)

! To improve absorption of food and reduce fluid loss in

short bowel syndrome

! Reduction of breakdown of pancreatic enzyme

supplements.

2. WHAT YOU NEED TO KNOW BEFORE YOU TAKE CIMETIDINE TABLETS

Do not take Cimetidine Tablets:

! If you are allergic to cimetidine or any of the other

ingredients of this medicine (listed in section 6).

If this applies to you, speak to your doctor or pharmacist.

Warnings and precautions

Talk to your doctor, pharmacist or nurse before taking Cimetidine Tablets if you:

! Suffer or have suffered in the past from kidney disease ! Have a history of peptic ulcer, particularly if you are taking

a non-steroidal anti-inflammatory drug (NSAID) e.g. aspirin, ibuprofen, naproxen, diclofenac

! Are taking drugs or you have an illness that could cause a

fall in blood cell count

! Are middle aged or over, with new or recently changed

indigestion symptoms (e.g stomach pain or discomfort, heartburn), then other causes of your symptoms such as stomach cancer, should be excluded

! If you are pregnant or planning a pregnancy ! If you are breast-feeding.

Other medicines and Cimetidine Tablets

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

may be affected by Cimetidine or they may affect how well Cimetidine will work.

In particular tell your doctor if you are taking any of the following:

! Anticoagulants to thin your blood e.g. warfarin. Your

doctor will monitor you

! Anticonvulsants to prevent fits e.g. phenytoin. Your doctor

will monitor you

! Bronchodilators for breathing difficulties e.g. theophylline ! Anti-arrhythmics to slow heart rate e.g. lidocaine,

propranolol

! Antidepressants to treat anxiety or depression e.g.

diazepam, amitriptyline

! Immunosuppressants to prevent organ rejection or

rheumatism (e.g. ciclosporin)

! Medicines that cause a fall in blood cell count ! Antifungals used to treat fungal infections (e.g.

ketoconazole, itraconazole or posaconazole) ! Antidiabetics to lower glucose levels in the blood (e.g.

metformin or glipizide)

! Anti-cancer drugs for the treatment of

cancer or tumors (e.g. carmustine,

fluorouracil, epirubicin, or therapies such as radiation)

! Strong pain killers (e.g. morphine)

! Antiretroviral drugs to treat HIV/AIDS (e.g

atazanavir)

! Tacrolimus used to treat eczema

! Medicines to treat heart problems e.g.

diltiazem, procainamide, metoprolol,

nifedipine.

Pregnancy and breastfeeding

DO NOT take Cimetidine if you are pregnant, planning to become pregnant or breast-feeding unless advised to by your doctor.

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 any medicine.

Driving and using machines

These tablets can cause some people to feel dizzy or drowsy. If you are affected do not drive or operate machinery.

Excipient information about Cimetidine Tablets

This medicine contains less than 1mmol of sodium per tablet, that is to say essentially 'sodium free'.

3. HOW TO TAKE CIMETIDINE TABLETS

Always take Cimetidine Tablets exactly as your doctor has instructed you. You should check with your doctor or pharmacist if you are unsure.

The usual dosage is 400mg to 1600mg cimetidine per day. Take twice a day with breakfast and at bedtime or as directed by your doctor. Swallow the tablets whole with a drink of water.

Do not take more than 2400mg cimetidine per day.

Elderly:

The normal adult dosage may be used unless you have kidney problems.

Use in children: your doctor will decide on the dose according to your child's body weight.

The usual length of treatment is at least four weeks though this may be longer in some conditions. Your doctor will advise you.

Patients with duodenal or gastric ulceration:

A single dose of 800mg at bedtime is recommended. Although your doctor may recommend 200mg three times a day with meals and 400mg at bedtime.

Patients with oesophageal reflux disease:

400mg four times a day with meals and at bedtime is recommended.

Patients with Zollinger-Ellison syndrome:

400mg four times a day with meals and at bedtime is recommended.

Patients with acid aspiration:

A dose of 400mg can be given 90-120 minutes before having a general anaesthetic or, in obstetric practice, at the start of labour. While there is still a risk of acid aspiration, a dose of up to 400mg may be repeated at 4 hourly intervals, as required, up to the usual daily maximum of 2.4g

Prevention of bleeding from stress ulcers in seriously ill patients:

200-400mg can be given every 4-6 hours

Patients with kidney problems

Doses may be reduced but your doctor will advise you on the amount to take.

If you take more Cimetidine Tablets than you should

This medicine is to be taken at regular intervals, as determined by the physician. If you take too many tablets by mistake contact your nearest hospital casualty department or tell your doctor immediately. Take your tablet pack with you. Do this even if you feel well.

If you stop taking Cimetidine Tablets

You may feel better after a few days, but you should keep taking your tablets until the prescribed course is finished. Your symptoms may come back if you stop your treatment too soon.

If you forget to take Cimetidine Tablets

If you forget to take a dose take it as soon as you remember, but if it is almost time for your next dose, skip the missed dose and continue as usual. Do not take a double dose to make up for a forgotten dose. If you have trouble remembering to take the tablets, tell your doctor or pharmacist.

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 everyone gets them.

Allergic reactions may occur rarely, with symptoms such as rash, itching, swelling of the face, wheeziness, shortness of breath, tightness in the chest, fever, low blood pressure and feeling dizzy particularly when standing up. If any of these occur STOP taking the medicine and contact a doctor immediately.

Common side effects (may affect up to 1 in 10 people):

! Headache

! Dizziness

! Diarrhoea

! Skin rash

! Myalgia (muscle aches)

! Tiredness.

Uncommon side effects (may affect up to 1 in 100 people):

! Leukopenia – decrease in the number of white blood cells ! Depression

! Confusion (usually in elderly or seriously ill) ! Hallucinations (hearing and seeing things that are not

there).

! Tachycardia (fast heartbeat)

! Liver disorder (hepatitis) stomach and abdomen

tenderness, loss of appetite, with or without jaundice (yellowing of the whites of the eyes and skin) ! Breast enlargement in men (gynaecomastia) – this is

usually reversible when the medicine is stopped ! Problems getting and maintaining an erection (impotence) ! Increase in plasma creatine levels.

Rare side effects (may affect up to 1 in 1,000 people):

! Thrombocytopenia – abnormally low number of platelets

in the blood

!· Aplastic anaemia – bone marrow disorder

!· Sinus bradycardia – slow heartbeat

! Increased serum transaminase levels which is reversible

when the medicine is stopped

! Kidney disorders (Interstitial nephritis with symptoms such

as blood in urine, increased or decreased urine output, nausea and vomiting).

Very rare side effects (may affect up to 1 in 10,000 people):

! Pancytopenia – blood disorder with low number of red and white blood cells and platelets

! Agranulocytosis – blood disorders with very low numbers of white blood cells

! Heart block – symptoms may include irregular heartbeats ! Inflammation of the pancreas – symptoms include stomach and back pain, nausea and vomiting ! Hair loss – reversible after treatment has stopped ! Arthralgia – aching muscles and joints

! Galactorrhoea – leakage of a milky substance from the breasts

! Fever.

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.

5. HOW TO STORE CIMETIDINE TABLETS

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

Check the expiry date printed on the label or side of the box. Do not use after the expiry date stated on the label. Store below 25°C. Protect from light.

Do not use this medicine if you notice any visible signs of deterioration.

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 Cimetidine Tablets contain:

Cimetidine Tablets 200, 400 and 800mg contain the active substance cimetidine 200mg, 400mg or 800mg in each film-coated tablet respectively.

The other ingredients are: Microcrystalline cellulose (E460), povidone 30, sodium starch glycollate, sodium lauryl sulphate, colloidal silicon dioxide, magnesium stearate, hydroxypropyl methylcellulose (E464), polyethylene glycol, quinoline yellow aluminium lake (E104), indigo carmine aluminium lake (E132), titanium dioxide (E171) and iron oxide yellow (E172).

What Cimetidine Tablets look like and contents of the pack

Cimetidine Tablets 200mg are pale green, circular, biconvex, film coated tablets, embossed with C1 on one side. Cimetidine Tablets 400mg are pale green, oval, film coated tablets, embossed with C2 on one side.

Cimetidine Tablets 800mg are pale green, oval, film coated tablets, embossed with C3 on one side.

Cimetidine 200mg Tablets are packed in cartons containing 12, 24, 48, 60 or 120 tablets in foil blister strips and in polypropylene tubes with pack sizes of 100, 250, 500 and 1000 tablets.

Cimetidine 400mg Tablets are packed in cartons containing 60 tablets in foil blister strips and in polypropylene tubes with pack sizes of 100, 250, 500 and 1000 tablets.

Cimetidine 800mg Tablets are packed in cartons containing 30 tablets in foil blister strips and in polypropylene tubes with pack sizes of 60, 100, 150, and 250 tablets.

Not all pack sizes may be marketed.

Marketing Authorisation Holder

Ennogen IP Ltd,

Unit G4, Riverside Industrial Estate,

Riverside Way, Dartford, DA1 5BS, UK

Manufacturer

Ennogen Healthcare International Ltd,

Unit G3, Riverside Industrial Estate,

Riverside Way, Dartford, DA1 5BS, UK.

This leaflet was last revised in June 2026.

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