BIOHACKPHARMStack Analyzer

Omeprazole and other proton-pump inhibitors (PPIs)

Losec, Prilosec, Omez, Ultop, Esomeprazole, Nexium, Pantoprazole, Protonix

Forms: Omeprazole, esomeprazole, pantoprazole, lansoprazole, dexlansoprazole, rabeprazole: capsules, tablets, granules, injections. Low-strength packs are sold without prescription in many countries; a tablet combining aspirin and omeprazole exists.

Health support (prescription)Over the counter (varies by country)Evidence: approved medicine

Drugs that block the stomach's acid pumps: the strongest standard treatment for reflux, heartburn and ulcers, and the usual stomach cover a doctor adds to aspirin or NSAIDs when ulcer risk is high.

Legal status: Low-strength packs are sold without prescription in many countries; higher strengths and long-term use are prescription (varies by country); not on the WADA Prohibited List.

What it gives

What people use it for and what the sources report. Strength is a general category from the literature: mild, clear or strong.

Purpose

Athletes turn to it for reflux and heartburn that hard training can bring on; in a stack its main role is stomach cover for aspirin or painkillers. A doctor adds it when ulcer risk is high (older age, past ulcer, other blood thinners). Medical use: reflux, ulcers, H. pylori treatment.

What people seek and what studies show

Strongly lowers stomach acid; heals reflux damage and ulcers (label). Hard exercise lowers the tone of the valve at the top of the stomach, which can bring reflux during training; data on PPIs for exercise-related symptoms come only from uncontrolled field studies. In heart patients on aspirin plus clopidogrel, omeprazole cut stomach events from 2.9% to 1.1% (COGENT). Not studied in PED users.

Effects

Side-effect controlOrgan & health-marker support

Evidence: Approved medicine — studied in people for its medical use

Sought effects by goal (as reported)

Health
Sought for: organ & health-marker support

Possible side effects

Possible does not mean certain: whether they appear depends on dose, duration, individual response and monitoring. Below — what to watch for and how to notice it early.

6 possible side effects

level · how often it is reported
Moderate
Infections, slower wound healing
Less acid lets more gut germs through: C. difficile diarrhea (label), enteric infections 1.4% vs 1.0% over 3 years in a large trial. Diarrhea that does not settle needs a doctor.
How to notice: More frequent or longer infections, thrush, cuts and wounds that heal slowly; fever can be masked.
rare
Moderate
Bone loss, fracture risk
Observational studies tie long-term or high-dose use to hip, wrist and spine fractures (label); a 3-year trial saw no rise. More reason for care in athletes with low energy availability (RED-S).
How to notice: Usually silent until a fracture; in training, bone pain that starts earlier each session, with a tender spot, can be a stress fracture.
rare
Moderate
Dehydration, electrolyte loss, cramps
Low magnesium is rare with prolonged use, more likely with diuretics; it can cause cramps, tetany, seizures or arrhythmias and drag down potassium and calcium (label).
How to notice: Cramps, thirst, weakness, dizziness, dark urine; power and endurance fall, especially in the heat.
rare
Moderate
Numbness, tingling, carpal tunnel
Years of acid suppression can impair vitamin B12 absorption (label); deficiency causes tingling, numbness and anemia. Symptoms like these deserve a B12 check.
How to notice: Numb or tingling fingers, especially at night.
rare
Moderate
Kidney strain
Acute interstitial nephritis, an allergic kidney inflammation, is a rare label warning. Hard training and big muscle mass also raise creatinine, so a doctor interprets tests.
How to notice: Usually silent; foamy urine or swelling in later stages. Big muscle mass or creatine also raise creatinine.
rare
Low
Nausea, GI upset, pancreatitis risk
Headache, belly pain, nausea, diarrhea or gas in a few percent of users (label); usually mild.
How to notice: Nausea, fullness, constipation or diarrhea; often worse in hard or long sessions.
possible

What the levels mean

Lowbackground — just be aware
Moderatewatch for signs
Elevatedneeds regular control
Highcritical — can be life-threatening or permanent

Level: general category from the literature, not your personal risk

How often

common
reported often
possible
reported in some people
rare
reported occasionally

How to lower the risks

For 6 of 6 possible side effects there are specific ways to lower the chance: everyday measures, supplements and options a doctor may consider. No measure removes a risk completely.

ModerateInfections, slower wound healing

Hand hygiene, enough sleep, vaccinations kept up to date (ask a doctor); no hard training or competing with fever; see a doctor early with fever or a wound that gets worse.

Measure
Hepatitis B vaccinationSleep hygieneSterile injecting equipment & needle-and-syringe servicesWorking with a doctor
Supplement or OTC product
ProbioticsVitamin C (ascorbic acid)Vitamin D3Zinc
How each option helps (8)
  • Hepatitis B vaccination — Very effective, but only against hepatitis B — not hepatitis C, HIV, abscesses or immunity lowered by corticosteroids. A blood test can show past infection or immunity; it need not delay vaccination.
  • Sleep hygiene — Short sleepers caught colds more often in a virus-exposure study, and IOC advice on illness in athletes includes enough sleep; it does not offset corticosteroids.
  • Sterile injecting equipment & needle-and-syringe services — Acts only on infections that come with injecting (skin infections, blood-borne viruses); it does nothing for the lowered immunity from corticosteroids, the main cause of this risk.
  • Working with a doctor — A doctor can bring vaccinations up to date, treat infections early and keep in mind that fever can be masked on corticosteroids; their immune suppression stays.
  • Probiotics — Some strains lower upper-respiratory infections in athletes (IOC: moderate support), strain-specific. Not shown to lower wound, skin or injection-site infections.
  • Vitamin C (ascorbic acid) — Under heavy physical stress (marathon runners, soldiers) regular intake roughly halved colds in trials; no effect in most people, on wound healing or on corticosteroid effects.
  • Vitamin D3 — A large analysis of trials found slightly fewer respiratory infections; the benefit is small and it does not offset corticosteroid immune suppression. A blood test shows if you are low.
  • Zinc — Zinc acetate lozenges may shorten a cold (IOC: moderate support); they do not make colds less frequent, and too much zinc weakens immunity. Corticosteroid effects stay.
ModerateBone loss, fracture risk

Strength and impact training, enough calcium and vitamin D from food, no smoking, enough energy for the training load (RED-S causes bone loss and stress fractures); with long-term use a doctor may order a bone density scan.

Measure
Avoiding alcohol and other liver stressorsWorking with a doctor
Supplement or OTC product
CalciumVitamin D3Vitamin K2 (and vitamin K)
How each option helps (5)
  • Avoiding alcohol and other liver stressors — Heavy drinking is a known risk factor for fractures and is part of the standard fracture-risk calculator; cutting it removes one added load on bone.
  • Working with a doctor — With long use of glucocorticoids, thyroid hormone or very low estrogen, a doctor can order a bone density scan and start treatment before a fracture.
  • Calcium — Enough calcium, best from food, is standard advice on glucocorticoids and for athletes eating too little; with vitamin D it cut stress fractures in recruits. Extra adds little if intake is enough.
  • Vitamin D3 — Keeping vitamin D normal is standard advice on glucocorticoids and for athletes eating too little; with calcium it cut stress fractures in recruits. Extra adds little if levels are normal.
  • Vitamin K2 (and vitamin K) — Fewer fractures were seen only in Japanese trials of a high-dose K2 form (MK-4) used there as a medicine; the MK-7 in most supplements has weak data for bone.
ModerateDehydration, electrolyte loss, cramps

Drink to thirst, more in heat and long sessions, with sodium-containing drinks; far beyond thirst risks low sodium. No weight cutting by dehydration. With diuretics, ARBs/ACE inhibitors or kidney problems: potassium products or salt substitutes only after a blood test and a doctor’s advice.

Measure
Fluid & electrolyte managementHeat acclimatisation & coolingRegular blood tests
Supplement or OTC product
Electrolytes (sodium, potassium, magnesium)MagnesiumMagnesium aspartateMagnesium carbonateMagnesium chlorideMagnesium citrateMagnesium gluconateMagnesium glycinate (bisglycinate)Magnesium lactateMagnesium malateMagnesium orotateMagnesium oxideMagnesium tauratePotassiumTaurine
How each option helps (18)
  • Fluid & electrolyte management — Weighing before and after training shows sweat loss; ACSM advises keeping it under about 2% of body weight. Salty fluids help, but they do not offset the losses diuretics cause.
  • Heat acclimatisation & cooling — Fluid and salt balance improves, but acclimatised athletes sweat more, so fluid needs go up, not down; it does not replace drinking or offset diuretic losses.
  • Regular blood tests — Sodium, potassium, magnesium and kidney tests catch dangerous shifts from diuretics, clenbuterol or thyroid hormone; they do not make those drugs safe.
  • Electrolytes (sodium, potassium, magnesium) — Replacing sweat sodium and fluid may lower the chance of dehydration and heat cramps; it does not remove heat-illness risk or make diuretics or water cuts safe, and its potassium is risky with ARBs.
  • Magnesium — Replaces magnesium lost in sweat or with diuretics; there is no good evidence that it stops exercise cramps. It does not make diuretic use or extreme weight cutting safe.
  • Magnesium aspartate — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium carbonate — Supplies magnesium, but it is used mainly as an antacid and there are few data on it as a supplement; chalk on the hands supplies none. Does not make diuretics safe.
  • Magnesium chloride — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium citrate — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium gluconate — Replaces magnesium lost in heavy sweat or with diuretics. Cochrane found no trials in exercise cramps; runners who cramped did not have lower blood magnesium. Does not make diuretics safe.
  • Magnesium glycinate (bisglycinate) — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium lactate — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium malate — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium orotate — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Magnesium oxide — Supplies some magnesium, but far less is absorbed than from soluble salts; Cochrane found no trials in exercise cramps. Does not make diuretics safe.
  • Magnesium taurate — Replaces magnesium lost in heavy sweat or with diuretics. A Cochrane review found no trials of magnesium for exercise-associated cramps. Does not make diuretics safe.
  • Potassium — Replaces potassium lost with sweat or thiazide and loop diuretics when a test shows it is low; it does not make diuretics safe and is risky with potassium-sparing ones.
  • Taurine — Used in practice against cramps on clenbuterol or diuretics; trials show fewer cramps only in liver disease, the clenbuterol link is rat data. Such cramps can mean low potassium: get a blood test.
ModerateNumbness, tingling, carpal tunnel

See a doctor: numbness from GH-type drugs often eases after stopping; other causes need tests — vitamin B12 on metformin, copper with long-term high-dose zinc.

Measure
Night wrist splint (carpal tunnel)Regular blood testsWorking with a doctor
Supplement or OTC product
Alpha-lipoic acidVitamin B12 (cobalamin)
How each option helps (5)
  • Night wrist splint (carpal tunnel) — In one small, low-quality trial a night splint more than tripled the chance of improvement; it eases nerve pressure, not GH-driven swelling, and does nothing for numbness from low B12.
  • Regular blood tests — Blood tests find treatable causes of numbness: low vitamin B12 on metformin, low copper from long-term zinc, high blood sugar.
  • Working with a doctor — Finds treatable causes of numbness early: low vitamin B12 on metformin, copper deficiency from excess zinc, nerve compression from GH-driven swelling.
  • Alpha-lipoic acid — Eased numbness and burning in diabetic nerve damage in trials (mostly as infusions); it has not been studied for numbness from GH-type drugs.
  • Vitamin B12 (cobalamin) — Corrects numbness caused by low vitamin B12, as can happen on long-term metformin; it does nothing for numbness from GH-type drugs, which is the usual cause on a stack.
ModerateKidney strain

Drink enough, more in heat; control blood pressure; avoid regular painkillers (NSAIDs) and any during long or hot events; no weight cutting by dehydration.

Measure
Fluid & electrolyte managementRegular blood testsWorking with a doctorHome blood-pressure monitoring
How each option helps (4)
  • Fluid & electrolyte management — Good hydration eases kidney stress from heavy training and heat; dehydration plus NSAIDs is a classic cause of acute kidney injury.
  • Regular blood tests — Creatinine runs high with big muscle mass, creatine and hard training, and standard eGFR formulas mislead in athletes; compare with your own baseline and add cystatin C and urinalysis.
  • Working with a doctor — Investigates protein in the urine or falling kidney function and can start treatment that slows kidney damage.
  • Home blood-pressure monitoring — Catches high blood pressure early — a main driver of kidney damage on steroids; it helps only if high readings lead to treatment.

Low-level side effects

Digestion
Smaller meals, enough fluid and fiber, test race-day food in training first; a doctor for severe abdominal pain.
Measure
Avoiding alcohol and other liver stressorsFluid & electrolyte managementWorking with a doctor
Supplement or OTC product
Famotidine (H2 blockers)LoperamideMacrogol (polyethylene glycol laxative)Magnesium carbonateMagnesium citrateMagnesium hydroxideMagnesium oxidePancreatin + dimeticone (Pankreoflat)ProbioticsPsyllium husk fiber
How each option helps (13)
  • Avoiding alcohol and other liver stressors — Alcohol irritates the stomach, adds to aspirin-related stomach bleeding and is a main cause of pancreatitis; avoiding it lowers that part of the risk, not drug nausea.
  • Fluid & electrolyte management — Dehydration makes gut complaints in long or hot sessions more likely; drinking enough helps that part, not nausea from drugs or pancreatitis.
  • Working with a doctor — Assesses persistent vomiting or severe belly pain (possible pancreatitis or gallstones), can add stomach protection to aspirin and adjusts GLP-1 treatment when nausea persists.
  • Famotidine (H2 blockers) — Relieves and prevents occasional heartburn (label); it does not help nausea or diarrhea. For reflux damage or long-term ulcer cover a doctor usually turns to a PPI.
  • Loperamide — Eases acute diarrhea, including on GLP-1 drugs (consensus), but not its cause; not for nausea or bloody stools. Fluids and salts still come first.
  • Macrogol (polyethylene glycol laxative) — Eases constipation, including on GLP-1 drugs, with strong guideline backing in chronic constipation; not for nausea or heartburn. Rectal bleeding or worsening pain needs a doctor.
  • Magnesium carbonate — An antacid for heartburn and indigestion (label), often combined with other antacids; it does not help nausea and may itself loosen stools. Not with weak kidneys.
  • Magnesium citrate — In larger amounts a saline laxative for occasional constipation (label); not for nausea. It causes cramps and loose stools itself; ask a doctor first with kidney disease.
  • Magnesium hydroxide — Labeled as an antacid for heartburn and a laxative for occasional constipation; short-term relief only, not for nausea. It can itself cause diarrhea; not with weak kidneys.
  • Magnesium oxide — An osmotic laxative that eases constipation (conditional guideline advice); not for nausea or heartburn. It loosens stools itself; with weak kidneys blood magnesium can rise.
  • Pancreatin + dimeticone (Pankreoflat) — Registered for heaviness and bloating after meals; it does not ease drug nausea, heartburn or aspirin stomach pain. Not with pork or cow's milk protein allergy or acute pancreatitis.
  • Probiotics — May ease diarrhea, for example on GLP-1 drugs (consensus); in sport studies they mostly did not reduce exercise gut symptoms. Not for nausea or heartburn.
  • Psyllium husk fiber — Soluble fiber eases constipation, including on GLP-1 drugs, and can firm loose stools; it does not help nausea or heartburn and can itself cause bloating and gas.

Check-ups and blood tests

Which tests and check-ups to do and when. This is a guide — agree the exact schedule with a sports physician.

Baseline tests
your own starting values — every later result is compared with them
Complete blood count (hematocrit, hemoglobin)Endurance training dilutes the blood (“sports anemia”), dehydration concentrates it — test hydrated and rested, against your own baseline.infections
Kidney panel (creatinine, eGFR, cystatin C)Creatinine reads higher with big muscle mass or creatine; cystatin C barely depends on muscle and helps judge the kidneys in athletes.kidneys, electrolytes
Electrolytes (potassium, sodium, magnesium)Low sodium after long events mostly comes from drinking far beyond thirst; heavy sweating in the heat also costs sodium.electrolytes
Home blood-pressure logMeasure seated and rested, not within 30 minutes after training, caffeine or smoking — they change the reading.kidneys
UrinalysisHard exercise can briefly put protein and blood into the urine, usually gone within a few days — test after rest and repeat before drawing conclusions.kidneys
Bone density scan (DXA) with long-term useIn athletes, a Z-score below −1 at the spine or hip, or a fall since the last scan, is a warning sign of low energy availability (RED-S, IOC tool).bones
While taking
about 4–6 weeks in, then every 6–8 weeks — agree the exact schedule with your doctor
Complete blood count (hematocrit, hemoglobin)Endurance training dilutes the blood (“sports anemia”), dehydration concentrates it — test hydrated and rested, against your own baseline.infections
Kidney panel (creatinine, eGFR, cystatin C)Creatinine reads higher with big muscle mass or creatine; cystatin C barely depends on muscle and helps judge the kidneys in athletes.kidneys, electrolytes
Electrolytes (potassium, sodium, magnesium)Low sodium after long events mostly comes from drinking far beyond thirst; heavy sweating in the heat also costs sodium.electrolytes
Home blood-pressure logMeasure seated and rested, not within 30 minutes after training, caffeine or smoking — they change the reading.kidneys
UrinalysisHard exercise can briefly put protein and blood into the urine, usually gone within a few days — test after rest and repeat before drawing conclusions.kidneys
After stopping
4–8 weeks after stopping (later after long-acting injections), then until values return to baseline
Complete blood count (hematocrit, hemoglobin)Endurance training dilutes the blood (“sports anemia”), dehydration concentrates it — test hydrated and rested, against your own baseline.infections
Kidney panel (creatinine, eGFR, cystatin C)Creatinine reads higher with big muscle mass or creatine; cystatin C barely depends on muscle and helps judge the kidneys in athletes.kidneys, electrolytes
Every year
with regular or repeated use
Bone density scan (DXA) with long-term useIn athletes, a Z-score below −1 at the spine or hip, or a fall since the last scan, is a warning sign of low energy availability (RED-S, IOC tool).bones

Which doctors can help

Nephrologistkidneys
Endocrinologistbones
Sports physiciannumbness

Get medical help at once if

  • Much less urine than usual, cola-colored urine (especially with severe muscle pain after hard training), new swelling, flank pain — see a doctor now.
  • Severe cramps, marked weakness, palpitations, dizziness on standing, very little urine — seek urgent care. Vomiting, confusion or a seizure after a long event can mean low sodium — do not drink more, call your local emergency number.
  • Bone pain that worsens with running or jumping — stop impact training and see a doctor soon; groin or hip pain on impact — urgent check for a femoral-neck stress fracture.
  • Fever with chills, fast breathing, confusion, or redness that spreads quickly — seek urgent care.

In an emergency, call your local emergency number.

For women

Epidemiologic data show no clear rise in birth defects with omeprazole in early pregnancy (label); still, ask a doctor if pregnant or breastfeeding.

Myth & fact

Myth

“Everyone on a stack should take omeprazole: it covers the stomach and liver from orals and painkillers.”

Fact

It lowers acid and the ulcer risk from aspirin or NSAIDs; guidelines reserve long-term use for people at real risk. It does nothing for liver strain from oral steroids, and long-term use has its own risks.

Combinations

CautionA PPI with a loop or thiazide diuretic

Prolonged PPI use can lower blood magnesium, and diuretics flush out magnesium and potassium as well. The omeprazole label names diuretics as a reason to consider checking magnesium. Low magnesium can bring cramps, tetany, seizures or arrhythmias and pull potassium and calcium down with it.

FurosemideHydrochlorothiazide

Check combinations →

Sources

DailyMed: Prilosec (omeprazole) prescribing information — warnings on C. difficile, fractures, B12, magnesium, nephritis (opens in a new tab)Freedberg et al., Gastroenterology 2017: risks and benefits of long-term PPI use (AGA best practice advice) (opens in a new tab)Moayyedi et al., Gastroenterology 2019: PPI safety in a 3-year randomized trial (COMPASS), only enteric infections higher (opens in a new tab)Bhatt et al., NEJM 2010: clopidogrel with or without omeprazole (COGENT) — fewer upper GI bleeds (opens in a new tab)DailyMed: aspirin and omeprazole tablets label — lower gastric ulcer risk in aspirin users at risk (opens in a new tab)Moayyedi et al., Am J Gastroenterol 2017: ACG and CAG clinical guideline on dyspepsia (PPI trial) (opens in a new tab)de Oliveira, Burini, Jeukendrup, Sports Med 2014: gastrointestinal complaints during exercise (reflux, NSAIDs) (opens in a new tab)Costa et al., Sports Med 2025: SDA/USSF position statement on exercise-associated GI symptoms (antacids, NSAIDs) (opens in a new tab)
Check how Omeprazole and other proton-pump inhibitors (PPIs) combines with your stack

Possible side effects by body system, combinations, how to lower the risks and which tests to do — free.

Open the stack check

Similar substances

ACE inhibitors (ramipril, perindopril, lisinopril)Altace, Tritace, CoversylSide-effect controlOrgan & health-marker supportAmlodipineNorvasc, Istin, Amlodipine besylateSide-effect controlOrgan & health-marker supportAspirin (acetylsalicylic acid)Aspirin Cardio, ASA, CardiomagnylOrgan & health-marker supportAtorvastatinLipitor, Sortis, LiprimarOrgan & health-marker supportSide-effect control