Updated 11 February 2013


Omeprazole is prescribed for a short period of time - usually 4-8 weeks - to treat ulcers of the stomach and the first part of the small intestine that connects to the stomach.


Omeprazole is the active ingredient of Adco-Omeprazole, Altosec, DRL-Omeprazole, Lokit, Losec, Nozer, Omez, Omiloc and Sandoz-Omeprazole.

General information

Omeprazole is prescribed for a short period of time - usually 4-8 weeks - to treat ulcers of the stomach and the first part of the small intestine that connects to the stomach (the duodenum). It is also effective in treating gastro-oesophageal reflux, the backward flow of stomach acid contents into the oesophagus (the tube that connects the mouth to the stomach).

It is prescribed for longer periods of time to treat patients with Zollinger-Ellison syndrome, a rare condition associated with a tumour that creates high levels of stomach-acid secretion.

In some cases, omeprazole is prescribed along with other medication (often two different antibiotics) to eradicate H. pylori, a cause of stomach ulcers. It is also registered for the short-term treatment of severe reflux oesophagitis in children older than 12 months.

For this drug to remain effective, it has to be taken regularly. An ulcer may recur when you stop treatment prematurely.

Omeprazole can mask the symptoms and may delay the diagnosis of stomach cancers. Possible malignancy should be excluded prior to the start of treatment.

How does omeprazole work?

This medication decreases the production of acid in the stomach as a result of blocking an enzyme needed for this process.

Fast facts

Drug schedule: schedule 4

Available as: omeprazole is available as capsules, tablets and as an injection

What does it do ? omeprazole reduces stomach-acid production

Overdose risk : low

Dependence risk: low

Is omeprazole available as a generic? yes

Is omeprazole available on prescription only? yes

User information

Onset of effect: within 3 hours

Duration of action: up to 24 hours

Dietary advice: take immediately before a meal; avoid food that may increase the production of stomach acid, i.e. alcohol, spicy meals etc.

Stopping this medicine: do not discontinue using this medication without consulting your prescriber as symptoms may recur with premature discontinuation

Prolonged use: although few problems are expected, omeprazole is not intended for indefinite use - a typical course of this medication is 8 weeks

Special precautions

Consult your doctor before using this drug if:

  • you have liver disease
  • you are taking any other medication

Pregnancy: avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.

Breastfeeding: avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.

Porphyria: avoid. This medication may cause serious adverse effects. Consult your doctor before use.

Infants and children: this medication is not intended for use in children and should only be prescribed by a paediatrician.

The elderly: no special precautions need to be taken.

Driving and hazardous work: caution is advised as use of this medication may lead to dizzines and/or light-headedness. Avoid such activities until you know how this medication affects you.

Alcohol: avoid concomitant use of alcohol with this medication as it may aggravate your condition and reduce the apparent efficacy of this medication.

Possible side effects:

Side effect


Consult your doctor



Only if severe

In all cases







nausea/ vomiting






skin rash



abdominal pain/ flatulence







Drug interactions:


increased risk of warfarin toxicity


increased risk of phenytoin toxicity

ketoconazole; itraconazole

reduced effect of these anti-fungal drugs


increased risk of benzodiazepine toxicity


increased risk of digoxin toxicity


increased reports of confusion, unusual muscle movement


increased risk of tacrolimus toxicity


increased risk of ciclosporin toxicity

Disease interactions

Consult your doctor before using this drug if you have liver disease.

Overdose action

A small overdose is no cause for concern. In case of intentional large overdose, seek emergency medical attention.

Recommended dosage

Adults: 10-40mg once daily. Maximum daily dose: 120mg

Children, 10-20kg: 10-20mg once daily

Children, > 20kg: 20-40mg once daily

This material is not intended to substitute medical advice, but is for informational purposes only. Please consult a physician for specific treatment and recommendations.


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