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Prilosec Side Effects
For people taking Prilosec, side effects that are relatively common include things such as headaches, diarrhea, and dizziness. In most cases, side effects associated with Prilosec are minor, meaning that they require no treatment or may be easily treated. However, you should notify your healthcare provider immediately if you develop more serious side effects, such as depression, fever, or signs of an allergic reaction.
As with any medicine, side effects are possible with Prilosec® (omeprazole). However, not everyone who takes the medication will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or are easily treated by you or your healthcare provider.
(This article covers many, but not all, of the possible side effects with Prilosec. Your healthcare provider can discuss a more complete list of Prilosec side effects with you.)
Prilosec has been studied thoroughly in clinical trials, in which the side effects of a group of people taking the drug are documented. In these studies, the most common side effects of Prilosec included:
- Headaches -- in up to 6.9 percent of people
- Abdominal pain (or stomach pain) -- up to 5.2 percent
- Diarrhea -- up to 3.7 percent
- Upper respiratory tract infections, such as the common cold -- up to 1.9 percent
- Dizziness -- up to 1.5 percent
- Constipation -- up to 1.1 percent
- Back pain -- up to 1.1 percent.
Some side effects of Prilosec, while occurring infrequently, are potentially serious and should be reported immediately to your healthcare provider. These include, but are not limited to:
- Depression, agitation, aggression, hallucinations, or confusion
- Symptoms of an inflammation of the pancreas (pancreatitis), such as:
- Nausea
- Fever or chills
- Extreme pain in the upper abdomen
- A rapid heartbeat (tachycardia)
- Signs of liver damage, such as yellowing in the whites of the eyes or skin, dark urine, or upper abdominal pain (or stomach pain)
- Signs of an allergic reaction, including an unexplained rash, hives, itching, and unexplained swelling
- Broken bones (some studies suggest this or other similar medications may increase the risk of bone fractures)
- Signs of low blood magnesium (hypomagnesemia), such as:
- Muscle spasm
- An irregular heart rhythm (arrhythmia)
- Seizures.
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD



