Comprehensive medication guide to Magnesium Citrate including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
Typically not covered by insurance or Medicare Part D as an OTC product. Some Medicare Advantage plans include OTC benefits; some Medicaid programs cover prescribed OTCs. FSA/HSA eligible for eligible medical purchases without a prescription since the CARES Act.
Estimated Cash Pricing
$5–$15 retail OTC for a 10 fl oz liquid bottle; supplement capsules (60-count) cost $8–$30 depending on brand. As low as $6 with a GoodRx coupon and prescription at participating pharmacies.
Medfinder Findability Score
92/100
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Magnesium citrate is a compound formed by combining magnesium — an essential mineral — with citric acid. It serves two distinct purposes: as a saline osmotic laxative for constipation and colonoscopy bowel preparation, and as a dietary supplement to replenish magnesium levels in the body.
It is available entirely over the counter in the United States — no prescription required. Brand names include Citroma, Citrate of Magnesia, and ColonX. Generic store brands from Walmart (Equate), CVS, Walgreens, and Target (Up & Up) contain the same active ingredient at the same concentration.
Magnesium is an essential mineral involved in over 300 enzymatic processes. Surveys suggest that a significant proportion of American adults fail to meet the recommended dietary allowance (RDA) of 310–420 mg/day, making magnesium citrate one of the most popular supplement choices due to its high bioavailability (20–40% absorption rate).
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As a laxative, magnesium citrate works through osmosis. The magnesium and citrate ions are only partially absorbed in the small intestine; the remainder draws water from surrounding tissues into the intestinal lumen by osmotic pressure. This increase in water volume softens stool, expands the bowel, and triggers peristaltic contractions — producing a bowel movement within 30 minutes to 6 hours.
As a supplement, magnesium citrate is absorbed in the small intestine — approximately 20–40% of the magnesium is taken up into the bloodstream. This bioavailability is significantly higher than magnesium oxide (~4–10%), making it one of the most efficient supplement forms. Once absorbed, magnesium acts as a cofactor for over 300 enzymatic reactions, supporting energy production (ATP synthesis), muscle contraction and relaxation, nerve function, cardiovascular health, bone structure, and blood sugar regulation.
The high solubility of the citrate salt in stomach acid is what makes this form so bioavailable — it readily dissociates into free magnesium ions that can be absorbed across the intestinal wall.
1.745 g/30 mL — oral liquid
10 fl oz bottle — standard laxative/colonoscopy prep dose
100 mg — capsule
Magnesium supplement capsule
125 mg — capsule
Magnesium supplement capsule
133.3 mg — capsule
Magnesium supplement capsule
100 mg — tablet
Magnesium supplement tablet
34–85 mg — chewable tablet
Lower-dose chewable magnesium supplement
Magnesium citrate is among the most accessible OTC medications in the United States. As of 2026, there is no FDA-declared shortage. Multiple manufacturers produce it, and it is distributed broadly through every major pharmacy chain (CVS, Walgreens, Rite Aid), big-box retailers (Walmart, Target, Costco), and most grocery stores. The findability score is 92/100 — meaning it is widely stocked with only rare, brief local gaps.
Local out-of-stock situations do occur, most commonly around colonoscopy prep demand clusters, holiday constipation spikes, and wellness supplement surges. When one store is out, another nearby usually has it. The key is knowing where to look — grocery stores and big-box retailers often have stock when dedicated pharmacy chains temporarily run low.
If you're having difficulty finding magnesium citrate in stock, medfinder can call pharmacies near you and text you the results — no hold music, no wasted trips.
Magnesium citrate is not a controlled substance and has no DEA scheduling requirements. Any licensed prescriber can write a prescription for it, though in most cases no prescription is needed — it is freely available over the counter. A prescription may be written to enable GoodRx coupon pricing, FSA/HSA reimbursement, or insurance documentation.
Telehealth providers can also prescribe magnesium citrate during a routine video or text consultation — platforms like Teladoc, MDLive, and Amazon Clinic are all options for patients who need a written prescription quickly.
No. Magnesium citrate is not a controlled substance and has no DEA scheduling. It is an over-the-counter product available without a prescription at any pharmacy, grocery store, or big-box retailer in the United States.
There are no special prescribing requirements, refill restrictions, or quantity limits associated with magnesium citrate. Any licensed healthcare provider (physician, NP, PA) can write a prescription for it if needed for insurance, FSA/HSA, or coupon purposes. However, a prescription is not required to purchase or use the product.
At laxative doses, these side effects are expected and usually mild:
Serious side effects — seek medical attention immediately:
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MiraLAX (polyethylene glycol 3350)
Osmotic laxative; gentler, 1–3 day onset, safer for kidney patients
Bisacodyl (Dulcolax)
Stimulant laxative; 6–12 hours oral, 15–60 min suppository; no kidney concerns
Senna (Senokot, Ex-Lax)
Stimulant laxative; 6–12 hours; plant-based, widely available
Magnesium Glycinate
Supplement alternative with similar bioavailability but much less laxative effect; preferred for sleep and daily use
Milk of Magnesia (magnesium hydroxide)
Saline laxative — closest substitute; same 30 min–6 hour onset; same kidney cautions
Prefer Magnesium Citrate? We can find it.
Eltrombopag (Promacta)
majorContraindicated interaction — magnesium markedly reduces eltrombopag absorption. Separate by at least 4 hours.
Dolutegravir (Tivicay)
majorCation binding reduces absorption. Take dolutegravir 2 hours before or 6 hours after magnesium citrate.
Bictegravir (Biktarvy)
majorCation binding reduces absorption. May take bictegravir 2 hours before; avoid simultaneous use.
Baloxavir marboxil (Xofluza)
majorCation binding significantly reduces antiviral plasma levels. Avoid or use alternate laxative.
Tetracycline antibiotics (doxycycline, minocycline)
majorInhibits GI absorption. Separate by at least 2 hours.
Fluoroquinolones (ciprofloxacin, levofloxacin)
majorReduces antibiotic bioavailability by up to 90%. Take antibiotic 2 hours before or 6 hours after.
Bisphosphonates (alendronate)
moderateInhibits GI absorption. Separate by at least 2 hours.
Calcium channel blockers (verapamil, amlodipine)
moderatePossible additive hypotension or muscle weakness via calcium pathway effects.
Neuromuscular blocking agents
moderateMay enhance neuromuscular-blocking effect. Inform anesthesiologist if large-dose magnesium was recently taken.
Magnesium citrate is one of the most versatile and accessible OTC medications available. Whether you're using it for occasional constipation, colonoscopy prep, or daily magnesium supplementation, it is safe, effective, and affordable for most people when used correctly.
Key safety reminders: avoid it if you have chronic kidney disease (CKD Stages 3–5), separate it from antibiotics and HIV medications by at least 2 hours, and do not use the laxative dose for more than 1 week without consulting a healthcare provider.
If you ever have difficulty locating magnesium citrate at your local pharmacy, medfinder will call pharmacies near you to find where it's in stock and text you the results.
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Our medication guides are researched and written to help patients make informed decisions. All content is reviewed for accuracy and updated regularly. Learn more about our standards
Real-time availability
Medfinder is actively checking pharmacy inventory for Magnesium Citrate. We don't publish a number until we have enough verified pharmacy checks to be accurate — start a search and our team confirms current availability near you, usually within 24 hours.
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