Free Tool
Supplement Interaction Checker
Add the supplements and medications you're taking. We'll check them against a curated database of 105 documented interactions — including dangerous combinations, absorption conflicts, timing issues, and beneficial synergies. Every entry has a cited source.
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Add two or more substances below to check for interactions.
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Browse all 105 interactions
Filter by severity or search by substance name. Each entry links to the full page with mechanism, dose guidance, and cited sources.
- Danger5-htp+ssri
Risk of serotonin syndrome
- Dangerbirth control+st johns wort
St John's wort reduces oral contraceptive effectiveness and has caused breakthrough bleeding and unintended pregnancies.
- Dangercyclosporine+st johns wort
St John's wort substantially lowers cyclosporine levels and has caused documented transplant rejection.
- Dangerdan shen+warfarin
Salvia miltiorrhiza potentiates warfarin
- Dangerginkgo biloba+aspirin
Ginkgo + Aspirin: High bleeding risk
- Dangerginseng+maoi
Ginseng may cause hypertensive crisis with MAOIs
- Dangerkava+benzodiazepines
Kava + Benzos: Excessive sedation risk
- Dangernattokinase+blood thinners
Nattokinase has potent blood-thinning properties
- Dangerpotassium+ace inhibitors
Risk of dangerous hyperkalemia
- Dangerpotassium+arbs
ARBs + Potassium: Hyperkalemia risk
- Dangersam-e+ssri
SAM-e with SSRIs: Serotonin syndrome risk
- DangerSSRI+st johns wort
Combining St John's wort with any SSRI risks serotonin syndrome — a potentially fatal hyperserotonergic state.
- Dangertyrosine+maoi
Tyrosine can cause hypertensive crisis with MAOIs
- Dangervitamin k2+warfarin
K2 also reverses warfarin's effect
- Warningantibiotics+iron
Fluoroquinolones and tetracyclines chelate iron
- Warningashwagandha+thyroid medication
Ashwagandha can raise thyroid hormone levels and stack additively with levothyroxine, risking thyrotoxicosis.
- Warningashwagandha+sedatives
May enhance sedative effects
- Warningastragalus+immunosuppressants
Astragalus is immunostimulating
- Warningberberine+metformin
Berberine has metformin-like glucose lowering
- Warningblood thinners+ginkgo biloba
Ginkgo may modestly increase bleeding risk with warfarin, aspirin, or clopidogrel. Evidence is mixed but precaution is warranted.
- Warningcalcium+iron
Calcium significantly reduces iron absorption
- Warningcalcium+thyroid medication
Calcium blocks thyroid medication absorption
- Warningchromium+insulin
Chromium may enhance insulin sensitivity
- Warningdong quai+warfarin
Dong quai contains natural coumarins and has potentiated warfarin in a published case, raising bleeding risk.
- Warningechinacea+immunosuppressants
Echinacea may counteract immunosuppressants
- Warninggarlic+warfarin
Garlic supplements increase bleeding risk
- Warninggrapefruit+calcium channel blockers
Grapefruit dramatically increases drug levels
- Warningiodine+thyroid medication
Iodine supplementation can destabilize thyroid
- Warningiron+thyroid medication
Iron reduces levothyroxine absorption
- Warninglicorice+blood pressure medications
Licorice raises blood pressure, opposing medication
- Warningomega-3+warfarin
Fish oil may increase bleeding risk with warfarin
- Warningppi+vitamin b12
Long-term PPI use reduces B12 absorption
- Warningppi+magnesium
PPIs can cause hypomagnesemia
- Warningtryptophan+5-htp
Both increase serotonin - risk of excess
- Warningtyrosine+5-htp
Tyrosine and 5-HTP compete for brain uptake
- Warningvalerian+sedatives
Valerian adds to sedative medication effects
- Warningvitamin b12+antacids
Long-term antacid use depletes B12
- Warningvitamin e+warfarin
High-dose vitamin E increases warfarin bleeding risk
- Warningvitamin k+warfarin
Vitamin K directly antagonizes warfarin. Consistency of intake, not avoidance, is the right clinical approach.
- Warningzinc+copper
Zinc depletes copper over time
- Cautionalpha lipoic acid+diabetes medications
ALA lowers blood sugar - may enhance diabetes meds
- Cautionantibiotics+probiotics
Antibiotics kill probiotic bacteria if taken together
- Cautionashwagandha+ssri
Ashwagandha may enhance SSRI effects
- Cautionbitter melon+diabetes medications
Bitter melon has glucose-lowering effects
- Cautioncalcium+magnesium
High calcium can impair magnesium absorption
- Cautioncalcium+zinc
Calcium may reduce zinc absorption
- Cautionchromium+metformin
Chromium adds to metformin's glucose-lowering effect
- Cautioncreatine+caffeine
Caffeine may blunt some creatine effects
- Cautiondiphenhydramine+melatonin
Both cause sedation - enhanced drowsiness
- Cautionfenugreek+diabetes medications
Fenugreek fiber slows glucose absorption
- Cautionfiber+medications
Fiber can reduce medication absorption
- Cautionfiber+minerals
Fiber can reduce mineral absorption
- Cautionginger+warfarin
Ginger may enhance anticoagulant effect
- Cautiongymnema+diabetes medications
Gymnema reduces sugar absorption and cravings
- Cautionhawthorn+blood pressure medications
Hawthorn adds to BP lowering effect
- Cautioniron+antacids
Antacids significantly reduce iron absorption
- Cautioniron+fiber
Phytates in fiber reduce non-heme iron absorption
- Cautionmagnesium+calcium channel blockers
Magnesium may enhance BP lowering effect
- Cautionmagnesium+antacids
PPIs impair magnesium absorption
- Cautionmagnesium+thyroid medication
Magnesium may reduce thyroid med absorption
- Cautionmelatonin+blood thinners
Melatonin may affect blood clotting
- Cautionmelatonin+ssri
Melatonin may enhance SSRI side effects
- Cautionnsaids+magnesium
NSAIDs may reduce magnesium levels
- Cautionomega-3+aspirin
Fish oil adds to aspirin's antiplatelet effect
- Cautionppi+calcium
PPIs reduce calcium carbonate absorption
- Cautionppi+iron
PPIs reduce non-heme iron absorption
- Cautionrhodiola+ssri
Rhodiola may have mild MAOI effects
- Cautionsoy+thyroid medication
Soy may interfere with thyroid medication
- Cautionvitamin c+vitamin b12
High-dose vitamin C may reduce B12 absorption
- Cautionvitamin e+vitamin k
High-dose vitamin E may interfere with vitamin K
- Cautionvitamin e+aspirin
Vitamin E enhances aspirin's antiplatelet effect
- Cautionzinc+iron
Zinc and iron compete for absorption
- Synergyacetaminophen+nac
NAC protects against acetaminophen liver damage
- Synergyashwagandha+black pepper
Piperine may enhance ashwagandha absorption
- Synergyboron+vitamin d
Boron extends vitamin D half-life
- Synergycollagen+vitamin c
Vitamin C is required for collagen synthesis
- Synergycoq10+statins
Statins deplete CoQ10 - supplementation recommended
- Synergycreatine+beta-alanine
Creatine and beta-alanine stack well for power + endurance
- Synergycreatine+hmb
HMB + creatine synergy for strength and lean mass
- Synergycurcumin+black pepper
Piperine increases curcumin absorption by 2000%
- Synergycurcumin+omega-3
Fat improves curcumin absorption
- Synergyglycine+magnesium
Both support sleep through different mechanisms
- Synergyiron+vitamin a
Vitamin A enhances iron absorption
- Synergyl-theanine+caffeine
L-theanine smooths caffeine's effects
- Synergymagnesium+vitamin d
Magnesium needed for vitamin D activation
- Synergymelatonin+magnesium
Complementary sleep support
- Synergynac+glutathione
NAC is the rate-limiting precursor to glutathione
- Synergyomega-3+vitamin e
Vitamin E protects omega-3 fats from oxidation
- Synergyquercetin+vitamin c
Vitamin C regenerates quercetin
- Synergyresveratrol+quercetin
Quercetin enhances resveratrol bioavailability
- Synergytaurine+magnesium
Taurine and magnesium support sleep and cardiovascular calm
- Synergyvitamin b12+folate
B12 and folate work together in methylation
- Synergyvitamin b6+magnesium
B6 enhances magnesium cellular uptake
- Synergyvitamin c+iron
Vitamin C dramatically enhances iron absorption
- Synergyvitamin d+vitamin k2
Vitamin D and K2 work synergistically
- Synergyvitamin d+calcium
Vitamin D enhances calcium absorption
- Synergyvitamin d+omega-3
Fat improves vitamin D absorption
- Synergyzinc+quercetin
Quercetin acts as zinc ionophore
- Synergyzinc+vitamin a
Zinc needed for vitamin A metabolism
- Infobcaa+tyrosine
BCAAs may reduce tyrosine brain uptake
- Infocalcium+antacids
Antacids reduce calcium absorption
- Infocoq10+blood pressure medications
CoQ10 may enhance BP medication effects
- Infocoq10+beta blocker
Beta blockers may deplete CoQ10
- Infomagnesium+zinc
High-dose magnesium may slightly reduce zinc absorption
- Infoselenium+thyroid medication
Selenium supports thyroid hormone conversion
What we track
- danger
- 14
- warning
- 26
- caution
- 32
- synergy
- 27
- info
- 6
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Medical disclaimer. This tool is for educational purposes only and does not replace advice from a qualified healthcare provider. Always consult your prescriber before combining supplements with prescription medication.