Zantac (Ranitidine Hydrochloride)

(℞) Prescription Required

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Zantac (Ranitidine Hydrochloride) Dosage and Side Effects

ZANTAC is used to heal ulcers in the stomach.

Proper Use of this medication

The usual dose is either:

  • 150 mg in the morning and 150 mg in the evening or,
  • 300 mg at bedtime

Your exact dose will depend on your particular stomach condition. Your doctor will tell you the dose you should take.

Swallow each tablet whole with some water.


If you take too much ZANTAC, contact your doctor or pharmacist for advice. If possible, show them the ZANTAC pack.

In case of drug overdose, contact a health care practitioner, hospital emergency department or regional Poison Control Centre immediately, even if there are no symptoms.

Side Effects

Side effects may include:

  • allergic reactions
  • skin rash
  • inflammation of blood vessels (vasculitis)
  • inflammation of the pancreas (pancreatitis)
  • inflammation of the liver (hepatitis), sometimes with yellowing of the whites of the eyes or skin (jaundice)
  • inflammation in the kidney (interstitial nephritis)
  • slow, fast or irregular heartbeat
  • diarrhea, constipation, nausea, vomiting, stomach pain
  • feeling confused, depressed, or excited, or seeing or hearing things that are not really there (hallucinations), trouble sleeping (insomnia); feeling sleepy (somnolence)
  • joint or muscle pain, malaise, uncontrolled movement
  • headache, dizziness, blurred vision
  • unusual hair loss or thinning (alopecia)
  • unable to get or maintain an erection (impotence)
  • unusual secretion of breast milk or breast enlargement in men

If you have any concerns about the side effects, tell your doctor, nurse or pharmacist.

Side effects that may show up in your blood tests:

  • changes to liver function
  • low levels of white blood cells
  • decrease in number of blood platelets (cells that help blood to clot)
  • decrease in number of all types of blood cells
  • small increase in the level of creatinine (a waste product) in your blood

Warnings and Precautions

BEFORE you use ZANTAC talk to your doctor or pharmacist if you:

  • have stomach cancer
  • have kidney disease, your doctor may lower your dose of ZANTAC
  • have a rare condition called acute porphyria (a blood disease)
  • have lung disease
  • are diabetic
  • have any problems with your immune system
  • have had stomach ulcers before and you are taking Non-Steroidal Anti-Inflammatory (NSAID) medicines
  • are pregnant, planning to become pregnant, breastfeeding or planning to breastfeed
  • are taking any other medications including NSAIDs

Under rare circumstances supervised by the doctor, H2-receptor antagonists such as ZANTAC might be used for long periods. Long term use of H2-receptor antagonists may prevent normal absorption of vitamin B12 from the diet and could lead to vitamin B12 deficiency. Talk to your doctor.

Interactions with this medication

Tell your doctor or pharmacist if you're taking any other medicines, if you’ve taken any recently, or if you start taking new ones. This includes medicines bought without a prescription. Some medicines can affect how ZANTAC works, or make it more likely that you’ll have side effects. ZANTAC can also affect how some other medicines work.

Drugs that may interact with ZANTAC include:

  • procainamide or n-acetylprocainamide (used to treat heart problems)
  • warfarin (used to thin the blood)
  • triazolam (used to treat insomnia)
  • midazolam (a sedative that may be given just before an operation)
  • ketoconazole (used to treat fungal infections)
  • atazanavir or delaviridine (used to treat HIV)
  • gefitinib (used to treat lung cancer)
  • Non-Steroidal Anti-Inflammatory (NSAID) medicines (used to treat pain and inflammation)
  • sucralfate (used to treat ulcers). Your doctor may advise that you take high doses or oral sucralfate (e.g. 2 g) at least 2 hours after ZANTAC administration.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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