Strontium citrate is sold over the counter in the U.S. as a bone health supplement, but its safety profile is not well established. The FDA has stated there is “insufficient information to know if the form of strontium in dietary supplements is safe.” Most of the safety data we have comes from studies on a prescription form called strontium ranelate, which was restricted in Europe after it was linked to increased risks of heart attack and blood clots. Whether those same risks apply to strontium citrate remains an open question, and the absence of clinical trials specific to the citrate form is itself a concern.
What Strontium Does in Bone
Strontium is chemically similar to calcium, and your body handles it in much the same way. When you take strontium, it gets incorporated into bone tissue by replacing some calcium atoms in the mineral structure. At the cellular level, strontium has a dual effect: it stimulates the cells that build new bone (osteoblasts) while slowing down the cells that break bone down (osteoclasts). This combination is unusual among bone treatments and is the main reason strontium has attracted interest for osteoporosis.
There is a strong correlation between strontium accumulation in bone and reduced fracture risk in postmenopausal women, though researchers debate how much of that benefit is structural versus purely chemical. Strontium is heavier than calcium, so when it replaces calcium in bone, it changes how bone density scans read. If just 1% of calcium atoms in bone are swapped for strontium, DXA scans overestimate bone mineral density by about 10%, even though the actual bone mass increases by only 0.5%. This means any improvement you see on a scan while taking strontium may be largely an artifact rather than a real gain in bone strength.
The Cardiovascular and Blood Clot Concerns
The most serious safety signals come from large clinical trials of strontium ranelate, the prescription form used in Europe. Pooled data from those trials showed an increased risk of venous thromboembolism (blood clots in veins) and pulmonary embolism (clots in the lungs), with the elevated risk appearing during the first year of use. Heart attack risk also rose: 1.7% of patients on strontium had a heart attack compared to 1.1% on placebo, a relative risk increase of about 60%.
In one five-year trial, for every 47 fewer non-spinal fractures prevented by strontium, there were 28 additional heart attacks and 16 additional cases of deep vein thrombosis or pulmonary embolism. In 2014, the European Medicines Agency’s safety committee quantified the tradeoff: for every 1,000 patient-years of treatment, strontium caused 4 extra cases of serious cardiac problems and 4 extra cases of blood clots, while preventing 5 non-spinal fractures, 15 spinal fractures, and less than 1 hip fracture. The committee recommended suspending the drug’s registration based on this unfavorable balance.
Notably, these increased risks of blood clots were not reported in the original published trial papers. Data on venous thromboembolism appeared in only 5 of 9 primary publications, and pulmonary embolism data in only 2 of 9. The cardiovascular risks surfaced through regulatory documents rather than the medical literature, meaning the risks were underreported for years.
Does Strontium Citrate Carry the Same Risks?
This is the central unanswered question. Health Canada conducted a safety review and found no reports of heart or circulatory side effects linked to strontium citrate, strontium lactate, or strontium gluconate at the time of their review. That sounds reassuring, but there’s an important caveat: the review also found no available data on cardiovascular risk with any non-ranelate form of strontium at any dose. The absence of reported harm is not the same as evidence of safety, especially when no one has run controlled trials to look for it.
Health Canada concluded that “a risk at lower doses of strontium ranelate and with other strontium salt combinations could not be ruled out.” The concern is straightforward. Once strontium citrate is absorbed and the citrate portion is separated, what remains is elemental strontium, the same element delivered by strontium ranelate. Standard supplement doses of strontium citrate (typically 680 mg of elemental strontium per day) deliver the exact same amount of elemental strontium as the prescription dose of strontium ranelate that triggered the European restrictions.
A Rare but Serious Skin Reaction
At least one case of DRESS syndrome has been reported with strontium citrate specifically. DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) is a severe, potentially life-threatening reaction involving widespread rash, fever, elevated liver enzymes, and abnormal white blood cell counts. A 51-year-old woman developed trunk and extremity eruptions with oral erosions six weeks after starting strontium citrate at 1.36 grams daily. Her symptoms resolved after stopping the supplement and receiving treatment. DRESS had already been documented with strontium ranelate in Europe, and this case confirmed the citrate form can trigger the same reaction.
The Dosage Problem
Most strontium citrate supplements sold in the U.S. deliver 680 mg of elemental strontium per day, which is 170 to 340 times the amount of strontium naturally found in the human diet. This is not a small nutritional top-up. It is a pharmacological dose, identical to what was used in the prescription drug trials that uncovered cardiovascular harm. Researchers have noted an increasing trend of patients self-administering strontium citrate to treat osteoporosis “naturally,” despite a lack of clinical data supporting its use for that purpose.
Case reports describe patients taking 680 mg daily of strontium citrate for years on their own initiative. Because strontium citrate is classified as a dietary supplement rather than a drug, it does not go through the same premarket safety testing that prescription medications require. The FDA does not evaluate supplements for efficacy or safety before they reach store shelves.
Who Should Avoid Strontium Citrate
Based on the restrictions placed on strontium ranelate in Europe, people with uncontrolled high blood pressure, a history of heart attack, stroke, peripheral artery disease, or any blood clotting disorder should not take strontium in any form. The European Medicines Agency explicitly contraindicated strontium ranelate in all of these groups. Since strontium citrate delivers the same element at the same dose, these restrictions are worth taking seriously even though they were written for a different formulation.
People with reduced kidney function face additional concern. The kidneys are the primary route for clearing strontium from the body, and impaired kidney function could lead to strontium accumulating to higher-than-intended levels, potentially amplifying any cardiovascular or clotting risks.
The Bone Scan Complication
If you are taking strontium citrate and monitoring your bone density with DXA scans, the results may be misleading. Strontium atoms are heavier than calcium, and when they replace calcium in bone tissue, they absorb more X-ray energy. This inflates the density reading on a scan without a proportional increase in actual bone strength. A 10% bump on your DXA report could reflect very little real change in fracture resistance. This makes it difficult for you or your doctor to know whether the supplement is genuinely helping.
The Bottom Line on Safety Evidence
Strontium citrate exists in a regulatory gap. It delivers a pharmacological dose of the same element that prompted European regulators to pull a prescription drug from the market, yet it is sold without prescription and without the clinical trial data that would clarify its risk profile. Health Canada found no adverse event reports for the citrate form but also found no data at all on its cardiovascular safety. The FDA has said the information is simply insufficient to determine safety. For someone considering strontium citrate for bone health, this is the core issue: the supplement has not been tested rigorously enough to confirm it is safe, and the closest available evidence, from the chemically related prescription form, raises legitimate concerns about heart attacks, blood clots, and severe skin reactions.