Omeprazole/Sodium Bicarbonate Side Effects: What to Expect and When to Call Your Doctor

Omeprazole/sodium bicarbonate (Zegerid) is generally well tolerated, and most people who take it for short-term treatment of GERD or ulcers experience few or no side effects. However, like all medications, it carries risks — some minor, and some that require medical attention.

This guide breaks down the full range of omeprazole/sodium bicarbonate side effects, from the common (and harmless) to the rare (and serious), so you know what to watch for.

Common Side Effects (Usually Mild and Temporary)

The most frequently reported side effects from clinical trials of omeprazole (the active ingredient in Zegerid) include:

• Headache — the most commonly reported side effect in clinical trials
• Diarrhea — usually mild and self-limiting; if severe or persistent, it may indicate a more serious issue (see below)
• Nausea — taking with food (when possible) may help reduce nausea, though Zegerid is meant to be taken before meals
• Abdominal pain or stomach discomfort
• Vomiting
• Flatulence (gas) — sodium bicarbonate can contribute to bloating and belching
• Constipation
• Upper respiratory symptoms — cough, sore throat (less common)

These side effects are generally mild and tend to improve as your body adjusts to the medication. If they are bothersome or don't resolve after the first week, contact your prescriber.

Important: The Sodium Content of Zegerid

Unlike plain omeprazole, Zegerid contains a significant amount of sodium. Each capsule contains 304 mg of sodium (from 1,100 mg of sodium bicarbonate); each suspension packet contains 460 mg of sodium. This is not listed as a "side effect" but is clinically important for:

• Patients on low-sodium diets (heart failure, hypertension, kidney disease)
• Patients with Bartter's syndrome, hypokalemia, or hypocalcemia — use with caution
• Patients with acid-base imbalance or metabolic alkalosis risk

Serious Side Effects: When to Call Your Doctor Immediately

Some side effects of omeprazole/sodium bicarbonate are rare but serious. Contact your healthcare provider right away if you experience any of the following:

• Signs of low magnesium (hypomagnesemia): Irregular or rapid heartbeat, muscle cramps or spasms, tremors, seizures, dizziness. More common with long-term use or in combination with diuretics.
• Clostridium difficile-associated diarrhea: Watery diarrhea, fever, severe abdominal cramping that doesn't resolve. PPIs can alter gut bacteria and increase C. diff risk.
• Kidney problems (acute interstitial nephritis): Blood in urine, decreased urination, swelling in the legs or feet, fever. Rare but can occur at any point during treatment.
• Severe skin reactions: Stevens-Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN), or DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms). These are rare but life-threatening. Symptoms: painful red or purple blistering skin rash, fever, mucous membrane involvement. Stop the medication and seek emergency care immediately.
• Lupus (cutaneous or systemic): New or worsening joint pain, skin rash on cheeks or arms that worsens in sunlight. Omeprazole has been associated with drug-induced lupus. Stop the medication and contact your doctor.
• Bone fractures: Long-term PPI use (more than 1 year, especially more than once daily) increases fracture risk at the hip, wrist, and spine. This is a risk to discuss with your doctor for long-term therapy, not an acute side effect.

Long-Term Risks to Know About

For patients who take omeprazole/sodium bicarbonate long-term, additional risks emerge:

• Vitamin B12 deficiency: With use of 3 years or longer, omeprazole can reduce vitamin B12 absorption. Symptoms include fatigue, numbness, memory problems. Periodic B12 monitoring may be warranted.
• Hypomagnesemia (low magnesium): More likely with long-term use or co-administration of diuretics
• Atrophic gastritis: Noted occasionally in long-term users in biopsy studies; clinical significance unclear
• Hyponatremia (low sodium in blood): Paradoxically, despite the high sodium content in Zegerid, chronic omeprazole use has been associated with hyponatremia in some patients

Who Should Be Extra Careful?

Discuss extra precautions with your doctor if you:

• Take clopidogrel (Plavix) — omeprazole reduces its effectiveness via CYP2C19
• Take rilpivirine or other HIV antiretrovirals — may be contraindicated
• Have kidney disease, heart failure, or hypertension (sodium content concern)
• Are pregnant or breastfeeding — no adequate human studies; weigh risks and benefits with your doctor
• Are over age 65 — increased sensitivity to side effects; monitor closely

The Bottom Line on Zegerid Side Effects

Most people take omeprazole/sodium bicarbonate without significant problems, especially for short courses. Side effects become a bigger consideration with long-term use. Work with your doctor to use the lowest effective dose for the shortest necessary time. And if you're concerned about interactions with your other medications, see our detailed guide on omeprazole/sodium bicarbonate drug interactions.