Proton pump inhibitor

Omeprazole: What to Know Before You Take It

Also sold as Prilosec

What Omeprazole Is Used For

Use(s) treats frequent heartburn (occurs 2 or more days a week) not intended for immediate relief of heartburn; this drug may take 1 to 4 days for full effect

Warnings

Warnings Allergy alert: do not use if you are allergic to omeprazole omeprazole may cause severe skin reactions. Symptoms may include: skin reddening blisters rash If an allergic reaction occurs, stop use and seek medical help right away. Do not use if you have: trouble or pain swallowing food, vomiting with blood, or bloody or black stools heartburn with lightheadedness, sweating or dizziness chest pain or shoulder pain with shortness of breath; sweating; pain spreading to arms, neck or shoulders; or lightheadednes frequent chest pain These may be signs of a serious condition. See your doctor. Ask a doctor before use if you have : had heartburn over 3 months. This may be a sign of a more serious condition. frequent wheezing, particularly with heartburn unexplained weight loss nausea or vomiting stomach pain Ask a doctor or pharmacist before use if you are taking a prescription drug. Acid reducers may interact with certain prescription drugs. Stop use and ask doctor if: your heartburn continues or worsens you need to take this product for more than 14 days you need to take more than 1 course of treatment every 4 months you get diarrhea you develop a rash or joint pain If pregnant or breast-feeding, ask a health professional before use. Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center right away (1-800-222-1222)

Omeprazole Drug Interactions (12)

Omeprazole + Clopidogrel

Omeprazole or Esomeprazole Avoid concomitant use of clopidogrel with omeprazole or esomeprazole.

Major interaction

Omeprazole + Aripiprazole

In addition, no dosage adjustment is necessary for substrates of CYP2D6 (e.g., dextromethorphan, fluoxetine, paroxetine, or venlafaxine), CYP2C9 (e.g., warfarin), CYP2C19 (e.g., omeprazole, warfarin, escitalopram), or CYP3A4 (e.g., dextromethorphan) when co-administered with aripiprazole.

Moderate interaction

Omeprazole + Phenytoin

Table 1: Drugs That Affect Phenytoin Concentrations Interacting Agent Examples Drugs that may increase phenytoin serum levels Antiepileptic drugs Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate Azoles Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole Antineoplastic agents Capecitabine, fluorouracil Antidepressants Fluoxetine, fluvoxamine, sertraline Gastric acid reducing agents H 2 antagonists (cimetidine), omeprazole Sulfonamides Sulfamethizole, sulfaphenazol…

Moderate interaction

Omeprazole + Tacrolimus

Mild or Moderate CYP3A Inhibitors: Clotrimazole, antibiotics (e.g., verapamil, diltiazem, nifedipine, nicardipine), amiodarone, danazol, ethinyl estradiol, cimetidine, lansoprazole and omeprazole May increase tacrolimus whole blood trough concentrations and increase the risk of serious adverse reactions (e.g., neurotoxicity, QT prolongation) [see Warnings and Precautions ( 5.7 , 5.10 , 5.11 )] .

Moderate interaction

Omeprazole + Atomoxetine

7.9 Drugs that Affect Gastric pH Drugs that elevate gastric pH (magnesium hydroxide/aluminum hydroxide, omeprazole) had no effect on atomoxetine bioavailability.

Minor interaction

Omeprazole + Carbamazepine

Drugs that have been shown, or would be expected, to increase plasma carbamazepine levels include aprepitant, cimetidine, ciprofloxacin, danazol, diltiazem, macrolides (e.g., erythromycin, clarithromycin), fluoxetine, fluvoxamine, trazodone, omeprazole, oxybutynin, isoniazid, niacinamide (nicotinamide), azoles (e.g., ketaconazole, itraconazole, fluconazole, voriconazole), acetazolamide, verapamil, ticlopidine, grapefruit juice, and protease inhibitors.

Minor interaction

Omeprazole + Clarithromycin

Proton Pump Inhibitors: Omeprazole No Dose Adjustment Omeprazole: The mean 24-hour gastric pH value was 5.2 when omeprazole was administered alone and 5.7 when coadministered with clarithromycin as a result of increased omeprazole exposures [see Pharmacokinetics ( 12.3 )] (see also Omeprazole under “Drugs That Affect Clarithromycin Tablets” in the table below).

Minor interaction

Omeprazole + Diazepam

At present, this reaction is known to occur with cimetidine, ketoconazole, fluvoxamine, fluoxetine, and omeprazole.

Minor interaction

Omeprazole + Digoxin

Conivaptan 33% 43% Diltiazem 20% NA Indomethacin 40% NA Mirabegron 29% 27% Nefazodone 27% 15% Nifedipine 45% NA Propantheline 24% 24% Quinine NA 33% Rabeprazole 29% 19% Saquinavir 27% 49% Spironolactone 25% NA Telmisartan 20 to 49% NA Tricagrelor 31% 28% Tolvaptan 30% 20% Trimethoprim 22 to 28% NA Digoxin concentrations increased, but magnitude is unclear Alprazolam, azithromycin, cyclosporine, diclofenac, diphenoxylate, epoprostenol, esomeprazole, ibuprofen, ketoconazole, lansoprazole, metfo…

Minor interaction

Omeprazole + Modafinil

Effects of Modafinil on CYP2C19 Substrates Elimination of drugs that are substrates for CYP2C19 (e.g., phenytoin, diazepam, propranolol, omeprazole, and clomipramine) may be prolonged by modafinil via inhibition of metabolic enzymes, with resultant higher systemic exposure.

Minor interaction

Omeprazole + Olanzapine

Inducers of CYP1A2 or Glucuronyl Transferase — Omeprazole and rifampin may cause an increase in olanzapine clearance.

Minor interaction

Omeprazole + Warfarin

Table 2: Examples of CYP450 Interactions with Warfarin Enzyme Inhibitors Inducers CYP2C9 amiodarone, capecitabine, cotrimoxazole, etravirine, fluconazole, fluvastatin, fluvoxamine, metronidazole, miconazole, oxandrolone, sulfinpyrazone, tigecycline, voriconazole, zafirlukast aprepitant, bosentan, carbamazepine, phenobarbital, rifampin CYP1A2 acyclovir, allopurinol, caffeine, cimetidine, ciprofloxacin, disulfiram, enoxacin, famotidine, fluvoxamine, methoxsalen, mexiletine, norfloxacin, oral co…

Minor interaction

Check Omeprazole against your full medication list in our free Interaction Checker

Most-Reported Side Effects

Based on 442,282 reports in the FDA Adverse Event Reporting System (FAERS). Reports do not prove the drug caused the effect.

chronic kidney disease36,790nausea26,696fatigue25,832diarrhoea25,257acute kidney injury23,856drug ineffective22,888dyspnoea20,797pain20,180headache19,136renal failure18,185vomiting17,163dizziness16,931

Explore full Omeprazole safety data in our free FDA Safety Explorer

FDA Recalls (5)

Class IIOngoingJun 30, 2025

Presence of foreign tablets/capsules: presence of foreign Divalproex Sodium Extended-Release 250mg tablet in a bottle of omeprazole capsules.

Recalling firm: Dr. Reddy's Laboratories, Inc.

Class IICompletedFeb 2, 2024

Subpotent Drug: Out of specification for assay

Recalling firm: Bausch Health Companies, Inc.

Class IITerminatedOct 5, 2021

CGMP Deviations: Customer complaint for the presence of a staple co-mingled with capsules within the bottle.

Recalling firm: Dr. Reddy's Laboratories, Inc.

Class IITerminatedMar 15, 2021

CGMP Deviations: Intermittent exposure to temperature excursion during storage.

Recalling firm: Cardinal Health Inc.

Class IITerminatedSep 16, 2013

Failed Tablet/Capsule Specification: some capsules over time do not meet or are suspected to not meet the specification for acid resistance.

Recalling firm: Kremers Urban Pharmaceuticals, Inc.

This information is educational — not medical advice.

This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

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