Supplement interaction checker.
Pick any two of 125 supplements and see whether they work better together, should be spaced apart, are redundant, or need caution, each explained with the evidence. 161 interactions and counting.
Free · no signup · evidence-led
Supplement interactions fall into four types: synergy (take them together), timing (space them apart), redundant (pick one), and caution (check with a clinician). For example, vitamin C boosts iron absorption, calcium blocks it, and CoQ10 with ubiquinol is redundant. Paste your full stack below to check yours free.
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Pick two supplements to see how they interact.
Use with caution
· 175-HTP + L-Tryptophan
Both raise serotonin, combining is rarely needed.
5-HTP + Saffron Extract
Both raise serotonin.
5-HTP + Mucuna Pruriens
Serotonin + dopamine push.
5-HTP + L-Tyrosine
Balance serotonin and dopamine precursors carefully.
Ginkgo Biloba + Nattokinase
Compounded blood-thinning effect.
Ginkgo Biloba + Aged Garlic Extract
Both can thin the blood.
Korean Red Ginseng + Theacrine
Stacked stimulation.
Nattokinase + Aged Garlic Extract
Stacked clot effects.
Omega-3 Fish Oil + Ginkgo Biloba
Both can thin the blood.
Omega-3 Fish Oil + Nattokinase
Compounded blood-thinning effect.
Omega-3 Fish Oil + Aged Garlic Extract
Mild additive thinning.
Red Yeast Rice + Niacinamide
Two lipid agents on the liver.
Rhodiola Rosea + Korean Red Ginseng
Two stimulating adaptogens.
Rhodiola Rosea + Theacrine
Energising stack.
Rhodiola Rosea + Caffeine + L-Theanine
Two stimulating compounds stack up.
Theacrine + Green Tea EGCG
Layered stimulants.
Vitamin E + Vitamin K2 MK-7
High-dose vitamin E can work against vitamin K.
Separate the timing
· 10Ashwagandha KSM-66 + Rhodiola Rosea
One calming, one stimulating adaptogen.
Beta-Alanine + Taurine
They compete for uptake.
Calcium + Magnesium Glycinate
Large calcium and magnesium doses can compete.
Calcium + Zinc Picolinate
Calcium blunts zinc absorption.
Green Tea EGCG + Iron Bisglycinate
Green tea tannins inhibit iron absorption.
Iron Bisglycinate + Calcium
Calcium blocks iron absorption by up to ~50%.
Iron Bisglycinate + Zinc Picolinate
High-dose iron and zinc compete for absorption.
Iron Bisglycinate + Magnesium Glycinate
Iron and magnesium can compete for absorption.
Iron Bisglycinate + Psyllium Husk Powder
Fibre can bind iron.
Zinc Picolinate + Magnesium Glycinate
Best taken a little apart at high doses.
Redundant together
· 16Acetyl-L-Carnitine + L-Carnitine Tartrate
Two forms of carnitine.
Alpha-GPC + Citicoline
Two choline donors.
BCAAs + Essential Amino Acids
EAAs already contain BCAAs.
CoQ10 + Ubiquinol
CoQ10 and ubiquinol are the same nutrient.
L-Citrulline Malate + L-Arginine
Citrulline raises arginine anyway.
Magnesium Glycinate + Magnesium Citrate
Two magnesium forms, usually one is enough.
Magnesium Glycinate + Magnesium L-Threonate
Overlapping magnesium forms.
Mucuna Pruriens + L-Tyrosine
Two dopamine precursors.
NMN + Nicotinamide Riboside
Two NAD+ precursors.
Omega-3 Fish Oil + Algae Omega-3 EPA/DHA
Two omega-3 sources doing the same job.
Resveratrol + Pterostilbene
Pterostilbene is methylated resveratrol.
Spirulina + Chlorella
Overlapping green algae.
Whey Protein Isolate + BCAAs
Whey is already rich in BCAAs.
Whey Protein Isolate + Plant Protein Blend
Two protein sources.
Whole-food Multivitamin + B-Complex
Overlapping B vitamins.
Whole-food Multivitamin + Biotin
Your multivitamin likely has biotin.
Works better together
· 1185-HTP + Vitamin B6
B6 helps convert 5-HTP to serotonin.
Alpha-Lipoic Acid + Acetyl-L-Carnitine
Classic mitochondrial pairing.
Alpha-Lipoic Acid + Glutathione
ALA helps recycle glutathione.
Artichoke Leaf Extract + Milk Thistle
Liver and bile support.
Ashwagandha KSM-66 + Melatonin
Both support sleep, different ways.
Ashwagandha KSM-66 + L-Theanine
Daytime stress pairing.
Ashwagandha KSM-66 + Magnolia Bark
Cortisol-lowering pair.
Ashwagandha KSM-66 + Magnesium Glycinate
An evening calm-and-sleep pair.
Bacopa Monnieri + Lion's Mane Mushroom
Memory plus nerve growth.
Bacopa Monnieri + Ginkgo Biloba
Memory plus circulation.
Beetroot Powder + L-Arginine
Blood-flow pairing.
Berberine HCl + Chromium Picolinate
Both support healthy blood sugar.
Berberine HCl + Red Yeast Rice
Lipid and glucose support.
Berberine HCl + Alpha-Lipoic Acid
Blood-sugar pairing.
Berberine HCl + Milk Thistle
Metabolic and liver support.
Berberine HCl + Ceylon Cinnamon
Blood-sugar support from two angles.
Berberine HCl + Chromium Picolinate
Two blood-sugar levers together.
Black Cohosh + Evening Primrose Oil
Menopause-symptom support.
Boron Glycinate + D-Aspartic Acid
Free-testosterone angle.
Boswellia + Curcumin
Anti-inflammatory pair.
Caffeine + L-Theanine + L-Theanine
The classic calm-focus stack.
Calcium + Vitamin K2 MK-7
K2 directs calcium to bone.
Calcium AKG + NMN
Longevity-stack pairing.
Chasteberry + Evening Primrose Oil
PMS-support pairing.
Choline Bitartrate + Omega-3 Fish Oil
Brain-building pair.
Chromium Picolinate + Alpha-Lipoic Acid
Glucose-metabolism pair.
Citicoline + Phosphatidylserine
Membrane and acetylcholine support.
Collagen Peptides + Vitamin C
Vitamin C is required to build collagen.
Collagen Peptides + Hyaluronic Acid
Skin-hydration pairing.
Collagen Peptides + Silica
Skin, hair, and nails.
Collagen Peptides + Biotin
Hair and nail support.
CoQ10 + PQQ
Mitochondrial duo.
CoQ10 + Omega-3 Fish Oil
Heart-health pairing.
Creatine Monohydrate + Beta-Alanine
Strength plus endurance, different systems.
Creatine Monohydrate + HMB
Build and protect muscle.
Creatine Monohydrate + Whey Protein Isolate
Classic muscle-building combo.
Creatine Monohydrate + Taurine
Cell hydration plus performance.
Curcumin + Omega-3 Fish Oil
Complementary anti-inflammatory effects.
Curcumin + Ginger Root Extract
Anti-inflammatory roots.
Dandelion Root + Milk Thistle
Traditional liver/detox pair.
Digestive Enzymes + Multi-Strain Probiotic
Digestion plus microbiome.
Elderberry Extract + Zinc Picolinate
Cold-season pairing.
Fisetin + Quercetin
Senolytic flavonoids.
GABA + L-Theanine
Calm-focus pairing.
Glucosamine + Chondroitin + MSM + MSM
Joint-support staple.
Glucosamine + Chondroitin + MSM + Boswellia
Structure plus anti-inflammatory.
Glucosamine + Chondroitin + MSM + Chondroitin Sulfate
The classic joint duo.
Glycine + Magnesium Glycinate
Calming sleep pairing.
Hawthorn Berry Extract + CoQ10
Heart-function pairing.
Huperzine A + Alpha-GPC
Raise and preserve acetylcholine.
Iron Bisglycinate + Vitamin C
Vitamin C dramatically boosts iron absorption.
Iron Bisglycinate + Methyl-B12
Both build healthy red blood cells.
Iron Bisglycinate + Vitamin A
Vitamin A helps your body use iron.
L-Citrulline Malate + Beetroot Powder
Nitric-oxide 'pump' pairing.
L-Citrulline Malate + Beta-Alanine
A core pre-workout combination.
L-Glutamine Powder + Zinc-Carnosine
Gut-lining support.
L-Theanine + Green Tea EGCG
Calm, focused energy together.
L-Theanine + Magnesium Glycinate
Relaxation without sedation.
L-Tryptophan + Vitamin B6
B6 aids tryptophan metabolism.
L-Tyrosine + Green Tea EGCG
Focus under stress.
L-Tyrosine + Caffeine + L-Theanine
Focus support under pressure.
Lion's Mane Mushroom + Alpha-GPC
Nootropic stack.
Lutein + Zeaxanthin + Astaxanthin
Eye-protection pairing.
Lutein + Zeaxanthin + Bilberry Extract
Vision support.
Maca Root + Tongkat Ali
Libido pairing.
Magnesium Glycinate + Vitamin D3 + K2
Magnesium helps your body use vitamin D.
Magnesium Glycinate + Vitamin B6
B6 helps magnesium get into your cells.
Magnolia Bark + GABA
Stress-and-sleep pairing.
Melatonin + Magnesium Glycinate
Sleep onset plus relaxation.
Melatonin + L-Theanine
Fall asleep faster, with a calmer mind.
Methylfolate + Methyl-B12
Folate and B12 work as a pair.
Milk Thistle + N-Acetyl Cysteine
Liver-support pair.
Multi-Strain Probiotic + Inulin
Synbiotic: probiotic plus its food.
Multi-Strain Probiotic + Saccharomyces boulardii
Bacteria plus beneficial yeast.
Multi-Strain Probiotic + Psyllium Husk Powder
Probiotic plus fibre.
N-Acetyl Cysteine + Glycine
GlyNAC, raises glutathione.
N-Acetyl Cysteine + Glutathione
Precursor plus the finished product.
Nettle Root Extract + Pumpkin Seed Oil
Urinary-support pair.
Nicotinamide Riboside + TMG
TMG supports methylation alongside NR.
NMN + TMG
TMG replaces methyl groups NMN uses up.
NMN + Resveratrol
Popular longevity pairing.
Omega-3 Fish Oil + Astaxanthin
Astaxanthin protects omega-3s.
Omega-3 Fish Oil + Vitamin E
Vitamin E guards omega-3s.
Omega-3 Fish Oil + Citrus Bergamot
Lipid-support pairing.
Omega-3 Fish Oil + Vitamin D3 + K2
A fat-soluble pair that absorbs best together.
Phosphatidylserine + Omega-3 Fish Oil
Brain-membrane pairing.
Quercetin + Zinc Picolinate
Quercetin helps zinc get into cells.
Quercetin + Vitamin C
Antioxidant plus recycling.
Red Yeast Rice + CoQ10
Red yeast rice can lower CoQ10.
Red Yeast Rice + Citrus Bergamot
Complementary cholesterol support.
Saw Palmetto Extract + Nettle Root Extract
Prostate-support pair.
Saw Palmetto Extract + Pumpkin Seed Oil
Prostate and urinary support.
Saw Palmetto Extract + Beta-Sitosterol
A prostate-comfort pairing.
Saw Palmetto Extract + Pygeum
Traditional prostate duo.
Selenium + Iodine
Thyroid pairing, but balance matters.
Spermidine + NMN
Autophagy plus NAD+.
Tart Cherry Extract + Omega-3 Fish Oil
Recovery pairing.
TMG + B-Complex
Both support methylation.
Tongkat Ali + Zinc Picolinate
Libido and testosterone support.
Tongkat Ali + Ashwagandha KSM-66
Testosterone and cortisol.
TUDCA + Milk Thistle
Bile and liver-cell support.
Ubiquinol + PQQ
Mitochondrial support.
Valerian Root + GABA
Sedative pairing.
Valerian Root + Passionflower Extract
Traditional sleep blend.
Valerian Root + Lemon Balm
Calming herbal pairing.
Vitamin A + Vitamin D3 + K2
Fat-soluble vitamins balance each other.
Vitamin B6 + Methylfolate
Team players for homocysteine.
Vitamin B6 + Methyl-B12
Nerve and energy support together.
Vitamin C + Vitamin E
They regenerate each other.
Vitamin C + Glutathione
Vitamin C spares glutathione.
Vitamin D3 + K2 + Calcium
Vitamin D drives calcium absorption.
Vitamin D3 + K2 + Boron Glycinate
Boron supports vitamin D status.
Vitamin E + Selenium
Antioxidant teammates.
Whey Protein Isolate + Creatine Monohydrate
Cornerstone muscle-building pair.
Zinc Picolinate + Vitamin C
Immune-support pairing.
Zinc Picolinate + D-Aspartic Acid
Testosterone-support pairing.
Zinc Picolinate + Vitamin C
A classic immune-support duo.
Zinc-Carnosine + DGL Licorice
Gut-lining soothers.
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Safe-stacking tips
Occasional, evidence-led emails on what works together, what to separate, and what to skip. No spam.
Common questions
Is there a free supplement interaction checker?
Yes. suppdoc's interaction checker is free, paste your supplements and we flag interactions, redundancies, and timing issues instantly, each explained with the evidence.
Which supplements should not be taken together?
Common ones to separate or reconsider include iron with calcium (timing), two omega-3 sources or CoQ10 with ubiquinol (redundant), and blood-thinning combinations like omega-3 with ginkgo (caution). See the full list below.
Educational use only, not medical advice. Interaction risk depends on dose, your health, and medications. Consult a qualified clinician before changing your supplements.