Magnesium salts

Dietary supplements provide elemental magnesium to support intake; their Supplement Facts amount is elemental magnesium, not the whole salt mass. This review does not establish FDA approval of supplements to treat disease. Prescription magnesium sulfate, OTC antacids and OTC laxatives have distinct labels and indications; an NDC listing or shared mineral name does not make them interchangeable.

Selected Method magnesium oxide is an OTC antacid for acid indigestion/upset stomach. Selected Phillips magnesium hydroxide and CareOne magnesium citrate are OTC saline laxatives for occasional constipation, usually producing a bowel movement within ½–6 hours. Their dose amounts are not a routine nutritional replacement recommendation or a universal bowel-preparation regimen.

Selected 50% sulfate concentrate is labeled for magnesium-deficiency replacement, TPN prevention/correction of hypomagnesemia, and prevention/control of preeclampsia/eclampsia seizures. The selected dextrose premix is specifically labeled for preeclampsia/eclampsia, including pregnant adolescents. It is not automatically labeled for every replacement or resuscitation use. No universal arrhythmia, asthma, fetal-neuroprotection or tocolysis regimen is supplied.

Reference intakes are total elemental magnesium from all sources, not prescribed supplement doses. Infant values are AIs; older ages use RDAs. The supplemental/nonfood UL is 65 mg/day at 1–3 years, 110 at 4–8 and 350 from 9 years onward, including pregnancy/lactation; no infant UL is established. The UL excludes naturally occurring food magnesium and does not replace supervised therapeutic drug dosing.

Phillips original: age 12+ uses 30–60 mL/day; age 6–11 uses 15–30 mL/day; under 6 asks a doctor. CareOne citrate: age 12+ uses 6.5–10 fluid ounces, maximum 10/24 hours; age 6 to < 12 uses 3–7, maximum 7; age 2 to < 6 uses 2–3, maximum 3; under 2 asks a doctor. These are different products/age boundaries. Shake, measure accurately and drink a full 8-ounce glass of liquid with each dose; do not exceed the daily maximum or self-use laxatives longer than 1 week.

Method magnesium oxide 400 mg contains 241.3 mg elemental magnesium per tablet. Its Drug Facts instructs one or two antacid tablets daily, maximumtwo unless physician-directed; no pediatric numerical regimen is provided. Phillips 15 mL contains 1200 mg hydroxide but 500 mg elemental magnesium. Selected citrate one fluid ounce (29.6 mL) contains 1.745 g citrate but 290 mg elemental magnesium. Salt mass and elemental mass must not be added as though identical.

50% means 500 mg magnesium sulfate heptahydrate per mL, not 500 mg elemental magnesium. The label states 1 g salt corresponds to about 8.12 mEq magnesium. Its adult mild-deficiency example is 1 g IM every 6 hours forfour doses; an alternative severe-deficiency example is 5 g diluted in 1 liter compatible fluid over 3 hours IV. TPN maintenance examples are adult 8–24 mEq/day and infant 2–10 mEq/day, individualized. These historical label examples are not a universal IV repletion algorithm; verify renal function, severity, volume tolerance and the hospital protocol. For IV administration, dilute 50% concentrate to 20% or less; the label generally limits IV rate to 150 mg salt/minute except its severe-eclampsia setting.

For the reviewed obstetric IV premix, loading is 4–6 g sulfate over 15 minutes, then 1–2 g/hour by infusion pump, adjusted to clinical status and serum magnesium. The label ceiling is 30–40 g/24 hours, not a daily target. Severe renal impairment and/or urine output < 0.5 mL/kg/hour uses an initial 4 g load and 1 g/hour maintenance with frequent reassessment, often requiring a lower maintenance dose; maximum 20 g/48 hours. This bag is 1 g/100 mL and requires no preinfusion dilution. Do not substitute the 50% concentrate’s IM regimen or another premix concentration/volume.

Selected parenteral labels contraindicate heart block or myocardial damage. The reviewed premix additionally contraindicates diabetic coma and myasthenia gravis; magnesium can precipitate respiratory failure/myasthenic crisis. Phillips prohibits prior product/ingredient allergy. Oral OTC labels direct kidney-disease patients to a clinician rather than supply a universal renal dose reduction. Do not treat an omitted contraindication in an older concentrate label as reassurance for myasthenia gravis.

The selected current sulfate injection/premix labels have no formal boxed warning; neither do the reviewed OTC Drug Facts products. Fetal-neonatal toxicity after prolonged pregnancy exposure, respiratory/cardiac toxicity and concentrate dilution warnings remain critical. No blanket boxed-warning statement is inferred for every product containing a magnesium salt.

Oral products can have laxative effects; excess oral intake commonly causes diarrhea, cramping or nausea. Systemic excess can produce flushing, sweating, hypotension, hyporeflexia, flaccid weakness, hypothermia, CNS/cardiac depression and respiratory paralysis; sulfate therapy can also cause hypocalcemia. Premix reports include pulmonary edema and myasthenic crisis. Precise event frequencies are not established by spontaneous reports.

Magnesium can impair oral tetracycline/quinolone or bisphosphonate absorption. NIH summarizes antibiotics 2 hours before or 4–6 hours after magnesium and bisphosphonates at least 2 hours apart; exact companion labels govern. Selected citrate directs separation from other medicines by at least 2 hours. A two-hour rule is not universal for all interacting drugs.

IV magnesium can prolong neuromuscular blockade and potentiate opioid/propofol or other CNS depression, requiring respiratory/neuromuscular monitoring and individualized companion adjustments. Dihydropyridine calcium-channel blockers may exaggerate hypotension. The selected premix specifically says not to combine with unapproved tocolytics such as terbutaline/nifedipine; this is distinct from monitoring other clinically justified BP combinations. Digitalized patients need extreme caution if calcium reversal becomes necessary.

Loop/thiazide diuretics and several other medicines can increase magnesium loss; long-term PPIs can cause low magnesium and require medication reassessment. IV mixtures can precipitate with incompatible products, including carbonates/salicylates and several calcium/phosphate-containing solutions; verify compatibility before sharing a line or TPN admixture rather than assuming every magnesium preparation mixes safely.

Use the exact OTC age bands above; selected antacid lacks a pediatric dose. Infant dietary AI/no established UL is not permission for unsupervised supplementation. The obstetric premix establishes pregnant-adolescent use with the same dose recommendations as pregnant adults; it does not establish general pediatric replacement dosing. Concentrate provides separate infant TPN examples and requires dilution to 20% or less for IM use in infants/children. Older adults may need lower parenteral doses because of reduced renal function.

Magnesium elimination depends on kidneys; impaired function increases toxicity risk. Oral OTC kidney-disease use needs clinician advice, and obstetric IV renal/oliguria schedules need frequent level/reflex/respiratory reassessment and reduced ceilings. Selected labels do not provide a validated hepatic-only reduction formula; liver disease with renal dysfunction or volume problems still requires clinical assessment. No dialysis or general chronic-CKD replacement algorithm is inferred.

Nutrition references above distinguish pregnancy and lactation from therapeutic dosing. OTC labels advise professional consultation. IV sulfate has obstetric seizure indications, but prolonged use beyond 5–7 days can harm fetal bone/mineral balance and cause neonatal respiratory/neuromuscular depression. The reviewed premix says milk magnesium rises only slightly and infant oral absorption is poor, while milk-production effects are unknown; the older concentrate advises caution during nursing. This is not a blanket permission for every salt or dose in pregnancy/lactation.

Magnesium participates in enzymatic reactions and neuromuscular transmission. Parenteral correction treats confirmed deficiency; anticonvulsant effects involve reduced neuromuscular transmission/acetylcholine release and CNS depression, with peripheral vasodilation. Magnesium hydroxide/citrate retain luminal fluid as saline laxatives; magnesium oxide neutralizes gastric acid as an antacid. These effects do not make all salts equivalent for each purpose.

Oral absorption differs with solubility/formulation; citrate/chloride/lactate/aspartate tend to be better absorbed than oxide/sulfate in small studies. IV bypasses absorption; IM sulfate anticonvulsant onset is slower than IV. Magnesium is renally eliminated, and the selected premix reports an average 4–5-hour half-life in preeclamptic women; that value is not universal for oral supplements or impaired kidneys.

Serum magnesium is useful but may not fully reflect body stores. Confirm units before interpreting mg/dL, mmol/L or mEq/L. The selected obstetric label considers 3–6 mg/dL (2.5–5 mEq/L) during seizure-control maintenance, which is a therapeutic context rather than a normal nutritional reference range. Falling reflex strength and respiratory depression can signal toxicity; do not pursue a concentration target without clinical assessment.

For replacement, assess symptoms, measured magnesium, renal function and relevant calcium/potassium abnormalities or losses. During parenteral therapy, follow levels, respiration, reflexes, BP and urine output; dextrose premix may require glucose surveillance. In OTC use, assess constipation duration, red-flag symptoms, kidney disease and concomitant medicines before repeated dosing. No single universal serum threshold or repletion schedule is supplied.

Read the actual Drug Facts/Supplement Facts, count elemental magnesium across products, and follow salt-specific directions. Seek urgent care for severe weakness, fainting, breathing difficulty or suspected overdose. Rectal bleeding or no bowel movement after laxative use requires medical assessment; persistent self-treatment beyond 1 week is inappropriate under the selected laxative labels. Do not use household oral salts as injectable products.

Discuss cation spacing with the pharmacist, including antibiotics and oral bone medicines, and disclose OTC laxatives/supplements before anesthesia or IV magnesium. Oral suspensions/liquids need accurate measurement and the labeled fluid intake. Hospital concentrate/premix therapy requires verified concentration, compatible line, infusion pump where labeled and immediate toxicity-response capability.

Phillips Original Milk of Magnesia is Bayer’s oral 1200 mg/15 mL hydroxide liquid; 355 mL bottle NDC 0280-0030-12. Selected Method oxide antacid bottle NDC 58657-120-12 contains 120 tablets. Selected Hospira concentrate is a 10 g/20 mL single-use vial, unit NDC 0409-2168-17; the WG obstetric premix is 1 g/100 mL, 24-bag carton NDC 44567-410-24. Verify actual manufacturer/device, not a generic salt-name appearance assumption.

Reviewed products include oral hydroxide suspension 1200 mg/15 mL, oral citrate 1.745 g/fl oz, oral oxide 400 mg/tablet (241.3 mg elemental), sulfate 50% concentrate 500 mg salt/mL, and selected IV dextrose premix 1 g salt/100 mL. The concentrate label states 49.3 mg elemental magnesium per mL; the premix provides 8.1 mEq/100 mL. Other oral salts/supplement forms and premix strengths exist but require their own verified composition; no common milliliter conversion applies.

Phillips is kept at room temperature, away from freezing and heat > 40°C, with cap tightly closed. Selected citrate is stored 8–30°C; Method oxide 15–30°C with intact seal. Selected concentrate and premix are stored 20–25°C; protect premix from freezing. Inspect injections for clarity/container damage, discard unused single-dose contents and avoid premix series connections. Concentrate must be diluted before IV use; premix requires no further dilution. Follow actual supplement/product package handling rather than impose a universal storage rule.