Use Omeprazole (Prilosec) to combat acid reflux

Omeprazole frequently is prescribed to treat acid reflux and stomach ulcers. It works by decreasing the amount of gastric acid produced by the stomach.

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Reviewed by Dr Roy Kedem, MD

Information last reviewed 10/31/19


What is Omeprazole?

Omeprazole is an FDA approved drug that is available both by prescription and over-the-counter. It is often used for the treatment of indigestion, acid reflux (heartburn), stomach ulcers, and sometimes used for prevention of cancer in the esophagus. Omeprazole is a type of medication known as a proton-pump inhibitor (PPI) which  works by reducing the production of acid in the stomach. It is therefore prescribed as a treatment for conditions in which the stomach produces excess acid, or when a reduction in the normal amount of acid production is required (such as with stomach ulcers).

Omeprazole can be used alone or with other medications to treat and prevent the return of ulcers caused by a type of bacteria (H. pylori), especially in adults. The nonprescription (over-the-counter) variety of the drug is used for the treatment of frequent heartburn; defined as heartburn occurring for 2 or more days in a week.

How does Omeprazole work?

Omeprazole is in a class of medications known as proton pump inhibitors. When taken orally, the medication works by blocking the activity of the proton pump (hydrogen-potassium [H-K] ATPase pump) in the stomach, which pumps out hydrogen ions, thereby reducing the amount of stomach acid. 

How effective is Omeprazole?

Omeprazole and other PPIs begin working within a few days to relieve the symptoms of indigestion or gastrointestinal reflux disease (GERD).  When taken at a standard dose for eight weeks, Omeprazole can heal erosive esophagitis in up to 86 percent of patients. Omeprazole and other PPIs are considered more effective than H2-blockers, such as Ranitidine, which reduce acid by blocking the activity of histamine in the stomach.


Active ingredients

The active ingredient in Omeprazole is omeprazole magnesium.

Inactive ingredients

The inactive ingredients in Omeprazole are: glyceryl monostearate, hydroxypropyl cellulose, hypromellose, magnesium stearate, methacrylic acid copolymer C, polysorbate, sugar spheres, talc, and triethyl citrate, and inactive granules.

Please note: The inactive ingredients may vary between different manufacturers.

Which ingredients can cause an allergic reaction?

In rare cases, omeprazole can cause a severe allergic reaction in people. Symptoms of a severe allergic reaction usually present itself a few minutes after consuming the medication. You should look out for swelling of the face or throat, hives, feeling dizzy, trouble breathing or itching of the skin. Call the emergency medical services if you notice any of these symptoms.


Before you start taking Omeprazole

Omeprazole can react with several medications, and some individuals may be allergic to omeprazole.  Before you begin treatment, there are a few things you should keep in mind:

  • Tell your doctor or pharmacist if you are allergic to Omeprazole, Dexlansoprazole (Dexilant), Esomeprazole (Nexium), Lansoprazole (Protonix), Rabeprazole (Aciphex), and any other medications or additional ingredients in the particular Omeprazole brand you will be taking. Your pharmacist can check the package for a comprehensive list of ingredients.
  • Make sure to tell your doctor if you are using Rilpivirine (Edurant, Complera, Odefsey). If you are taking Rilpivirine, your doctor will probably instruct you not to use Omeprazole.
  • Make sure you inform your doctor or pharmacist of any prescription and nonprescription medications, nutritional supplements, and herbal products that you might be taking or plan to take.
  • Inform your doctor if you are of Asian descent, if you have or have ever had low levels of magnesium in your blood, low levels of vitamin B-12, any autoimmune disease (conditions in which the body attacks its own organs or tissue, leading to inflammation and gradual loss of function), or osteoporosis (a condition in which the bones become weak and brittle).

How to use Omeprazole safely

Prescription Omeprazole is available as a delayed-release capsule or in packets of delayed-release granules.  The granules can be mixed in liquid and taken orally or through a feeding tube.  The nonprescription (over-the-counter) version of the drug is only available as a delayed-release oral tablet.

Note: The term delayed-release means the medication is designed to delay the release of a drug into the body, usually until it bypasses the stomach and enters the small intestine. This is to prevent the breakdown of the medication by stomach acids. It is, therefore, important that you never split or crush delayed-release medications, as this can cause you to absorb the medication too quickly, resulting in potentially dangerous side effects.
You should always read the patient information leaflet before taking Omeprazole, and you should read it again if you get a refill or new pack of Omeprazole, as the information is regularly updated. Reading the patient information leaflet will give you comprehensive information on how the medication should be used and describe potential side effects you may experience.

Additional antacids can be taken with Omeprazole if needed.  You should talk to your doctor if you feel you require more than one antacid as there may be an alternative diagnosis to your symptoms.  If you intend to use Sucralfate with Omeprazole, then Omeprazole must be taken at least 30 minutes before Sucralfate.

How regularly should Omeprazole be taken?

The dose and frequency of Omeprazole, which is recommended, or prescribed, will depend on the condition that you are treating.  Prescription Omeprazole should be taken at least 1 hour before a meal, once a day. It may be taken up to two times a day when used with other medication as a treatment to eliminate H. pylori, and up to three times a day before meals when used to treat less common conditions in which the stomach produces excess acid. Always follow your doctor’s instructions on how to take Omperazole.

The nonprescription, delayed-release tablets should be taken once a day in the morning, at least 1 hour before food.  A typical course lasts 14 days.  If additional treatment is needed, another 14-day course may be repeated, but not more than once every 4 months.  

It is a good idea to take your Omeprazole at around the same time every day to help remember when to take it.

Make sure you ask your pharmacist to explain anything you do not understand after reading the prescription label carefully.

What should I do if I forget a dose?

If you forget a dose of Omeprazole, take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take the next dose at your normally scheduled time. You should never double the dose to make up for the missed one. If you are unsure, you should speak to your doctor about this.

What should I do in case of an overdose of Omeprazole?

In case of an overdose, you should immediately call the poison control helpline at 1-800-222-1222, or its equivalence in your area. If you are witness to a victim of a suspected overdose who has collapsed and cannot breathe, or cannot be awakened, call emergency services immediately at 911.

Some of the symptoms of overdose include unusual sweating, confusion, blurred vision, and an unusually fast heartbeat.

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Side Effects

The use of Omeprazole can cause side effects. If you develop symptoms that are severe or persistent, tell your doctor immediately.

Common side effects

  • Constipation
  • Diarrhea
  • Vomiting
  • Headache
  • Nausea

Some side effects of Omeprazole can be serious. If you experience any of the following symptoms, speak to your doctor immediately or call Emergency Medical Services.

Uncommon/Severe side effects

  • Itching
  • Rash
  • Hoarseness
  • Dizziness
  • Lightheadedness
  • Uncontrollable shaking of any part of the body
  • New joint pain that progressively worsens
  • Traces of blood in the urine
  • Muscles spasms, weakness, and cramps
  • Feelings of excessive exhaustion
  • A decrease in the amount of urination
  • Difficult breathing
  • Swelling of any part of the body (i.e. face, lips, eyes, tongue, etc.)

Note: The above does not represent a complete list of side effects which can occur with use of Omeprazole. You should talk to your doctor if you notice any serious side effect, including any not mentioned in the above lists.

Additional considerations

People who take proton-pump inhibitors have a higher likelihood of fracturing their wrists, spine or hips compared with people who do not. Gland polyps (a growth on the lining of the stomach) can develop in people who take Omeprazole or other PPIs. People who take a high dose of Omeprazole or have been taking the medication long-term are likely to be at a higher risk of experiencing side effects.

Talk to your doctor about the risk of using Omeprazole and the ideal length of time you will need to take the medication.


You should make sure not to crush, chew, or break delayed-release tablets.  Doing so can cause the release of the entire drug at once, increasing the risk of serious side effects.

If you are taking disintegrating, delayed-release Omeprazole, make sure you handle the tablets with dry hands. To use this form of medication, you should place the tablet on your tongue and let it dissolve. The dissolved form of the tablet can be taken with or without water. The tablet can also be swallowed whole with water.

Nonprescription Omeprazole should not be taken for immediate relief of heartburn symptoms. It may take 1 to 4 days before the full benefit of the medication is felt. You should make sure you call your doctor if your symptoms get worse or do not improve after using the medication for 14 days, or if your symptoms return sooner than 4 months after you finish treatment.

Drug interactions

Many drugs can interact with Omeprazole and other proton-pump inhibitors. Always present a full list of medications and supplements that you are currently taking to your doctor or pharmacist before commencing Omeprazole.  

  • Acalabrutinib
  • Amphetamine
  • Antihepaciviral Combination Products
  • Atazanavir
  • Bisphosphonate Derivatives
  • Bosutinib
  • Capecitabine
  • Cefditoren
  • Cefpodoxime
  • Cefuroxime
  • Cilostazol
  • Citalopram
  • CloBAZam
  • Clopidogrel
  • CloZAPine
  • CycloSPORINE
  • Darunavir
  • Dasatinib
  • Delavirdine
  • Dexmethylphenidate
  • Dextroamphetamine
  • Doxycycline
  • Enzalutamide
  • Erlotinib
  • Escitalopram
  • Fluconazole
  • Fosphenytoin
  • Gefitinib
  • Indinavir
  • Itraconazole
  • Ketoconazole
  • Ledipasvir
  • Mesalamine
  • Methotrexate
  • Methylphenidate
  • Mycophenolate
  • Nelfinavir
  • Phenytoin
  • Posaconazole
  • Raltegravir
  • RifAMPin
  • Rilpivirine
  • Risedronate
  • SORAfenib
  • St John's Wort
  • Tacrolimus
  • Tipranavir
  • Velpatasvir
  • Vitamin K Antagonists (eg, warfarin)
  • Voriconazole


  • Any allergy (itching, bronchospasm, angioedema, anaphylaxis, kidney injury,) to Omeprazole or any component of its formulation/ingredients is a contraindication. 
  • Concomitant use with products containing Rilpivirine
  • Do not use if you have pain with swallowing food, vomiting blood, black stools, heartburn with lightheadedness, dizziness, chest pain, pain radiating to the arms or shoulders or trouble breathing, as these may be indications of a serious condition that should not be treated with proton pump inhibitors alone.  Seek immediate medical attention if you are experiencing these symptoms.


Disclaimer: This is not medical advice. You and your physician will determine if and how you should take any medication prescribed to you following a medical consultation.

  1. Omeprazole (Drugs and Medications), (2019). Retrieved from WebMD website:
  2. Omeprazole (Drugs, Herbs, and Supplements), (2019). Retrieved from MedlinePlus website:
  3. Prilosec (2019). Retrieved from RxList website:

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