supplement interaction
15 interactions related to supplement interaction
calcium + zinc
A large calcium dose may modestly reduce zinc absorption in some conditions, but human evidence is mixed and the effect is not clinically dangerous.
St. John's Wort + SSRI
St. John's Wort is pharmacologically active, not a harmless herb, and it interacts with SSRIs in two overlapping and hard-to-predict ways. The result is a combination most clinicians prefer to avoid rather than manage.
vitamin d + vitamin k2
Vitamin D and vitamin K2 act synergistically on calcium metabolism: vitamin D increases calcium absorption while vitamin K2 activates osteocalcin and matrix Gla protein to direct calcium into bone and away from soft tissue. The main caution is for people taking warfarin.
curcumin + piperine
Piperine (black pepper extract) substantially increases how much curcumin your body absorbs.
losartan + potassium
Losartan blocks the angiotensin II receptor, lowering aldosterone and reducing the amount of potassium the kidneys excrete. Adding concentrated potassium supplements or potassium-based salt substitutes can push serum potassium toward the hyperkalemic range, which carries cardiac arrhythmia risk in people with kidney impairment, diabetes, or heart failure. Routine monotherapy raises measured potassium only modestly in people with healthy kidneys, but the safety margin narrows once supplements or other potassium-raising drugs are added.
lisinopril + potassium
Lisinopril blocks the renin-angiotensin-aldosterone system, lowering aldosterone and reducing the kidneys' ability to excrete potassium. Adding a potassium supplement or potassium-based salt substitute on top can push blood potassium into a dangerous range (hyperkalemia), especially in older adults or people with reduced kidney function.
amlodipine + calcium
In theory, supplemental calcium could slightly blunt the blood-pressure-lowering effect of calcium channel blockers such as amlodipine, but controlled human data do not show a meaningful effect. Drugs.com flags this as a minor, monitor-only interaction with weak clinical evidence.
metformin + vitamin b12
Long-term metformin use can reduce vitamin B12 absorption, sometimes enough to cause deficiency.
metformin + alpha-lipoic acid
Metformin and alpha-lipoic acid both lower blood glucose by independent routes, so their effects can be additive. The added effect is mild for most people, but matters more in those also taking insulin or a sulfonylurea, or who are elderly, thin, or on a beta-blocker.
metformin + chromium
Chromium is sometimes taken to support blood sugar, and in theory it could add to metformin's glucose-lowering effect. In practice, human trials are mixed: some show a small improvement in insulin sensitivity while most show little or no change in actual blood glucose. The combination is generally well tolerated, but because both are aimed at the same goal, it is worth flagging to your prescriber and watching for any signs of a low.
valsartan + spirulina
Spirulina has a modest blood-pressure-lowering effect in clinical trials and contributes a small amount of potassium. Combined with valsartan, the theoretical concerns are slightly additive blood pressure lowering and a minor contribution to potassium load. At usual supplement amounts neither effect is large, and for people with normal kidney function the combination is generally tolerable.
trazodone + 5-htp
Both trazodone and 5-HTP raise serotonin activity, but through different routes. Trazodone is a serotonin antagonist and reuptake inhibitor that keeps more serotonin in the synapse, while 5-HTP is a direct precursor that increases how much serotonin the body makes. Stacking the two adds up, and major drug-interaction databases flag the pairing as a serious interaction because of the risk of serotonin syndrome.
tramadol + 5-htp
Tramadol blocks the reuptake of serotonin, and 5-HTP is a direct precursor that raises serotonin production in the brain. Stacking the two can push serotonin activity too high and trigger serotonin syndrome, a potentially life-threatening reaction.
ginseng + caffeine
Ginseng and caffeine are both mild stimulants, so combining them can additively increase alertness, jitteriness, palpitations, or insomnia in sensitive people, though the best evidence shows no meaningful cardiac signal from ginseng itself.
guarana + caffeine medications
Guarana seeds are an unusually concentrated source of caffeine, carrying several times the caffeine of coffee beans, and that caffeine adds directly to any caffeine-containing medication (such as Excedrin, Fioricet, Cafergot, Anacin, Esgic, NoDoz, or Vivarin). Because the caffeine is additive and easy to overlook, stacking guarana on top of these products can push total caffeine intake into a range linked to tachycardia, hypertension, jitteriness, GI upset, insomnia, and — in published case reports — serious cardiac arrhythmias.