Risky together20
- Acetaminophen (Paracetamol) + Alcohol (Ethanol)If you drink heavily most days, the manufacturer's own advice is to ask a doctor before using it at all, and that advice is worth following.
- Cannabidiol (CBD) + ClobazamAnyone taking clobazam should tell their prescriber before adding cannabidiol from any source, because the sedation is the signal that the metabolite has climbed and the prescriber may need to lower the clobazam dose.
- Cannabidiol (CBD) + ValproateAnyone on valproate should not add cannabidiol without their prescriber knowing, because that specific pair produced the highest rate of liver enzyme elevation in the trials and needs blood tests to catch.
- Diphenhydramine + Acetaminophen (Paracetamol)Read the active ingredients on anything labelled PM or night-time before taking anything else that evening, because the second ingredient is the one you did not choose.
- Diphenhydramine + Alcohol (Ethanol)Follow the label and keep the drink and the tablet apart, which costs nothing.
- Folic Acid + Vitamin B12Nothing changes for someone taking 400 micrograms of folic acid before and during a pregnancy.
- Glucosamine + WarfarinIf you take warfarin, tell whoever monitors it that you are taking glucosamine, and tell them again if you change the amount.
- Ibuprofen + NaproxenReading the active ingredient on a second pain, cold or flu product before taking it alongside the first is the whole of it.
- Sildenafil + Alpha-Blockers (Alpha-1 Adrenoceptor Antagonists)Say what else you are taking.
- Sildenafil + Organic Nitrates (Nitrovasodilators)Two things follow.
- Soy Isoflavones + LevothyroxineLevothyroxine is already meant to be taken on an empty stomach, away from food, for reasons that have nothing to do with soy.
- St John's Wort + CiclosporinAnyone on ciclosporin should not take St John's Wort.
- St John's Wort + Combined Hormonal ContraceptivesIf you are on a combined pill and you start St John's Wort, add a barrier method, and treat bleeding between periods as a signal rather than a nuisance.
- St John's Wort + DigoxinDigoxin has a narrow safe range and is monitored by blood test, so the practical point is timing.
- St John's Wort + HIV Antiretrovirals (Protease Inhibitors and NNRTIs)Do not combine St John's Wort with a protease-inhibitor or NNRTI-based regimen.
- St John's Wort + ImatinibDo not take St John's Wort with imatinib.
- St John's Wort + IrinotecanDo not take St John's Wort while on irinotecan, and tell the oncology team about any supplement started between cycles.
- St John's Wort + SSRIs (Selective Serotonin Reuptake Inhibitors)Do not add St John's Wort to an SSRI, and do not use it to self-manage coming off one, because tapering involves a period on both.
- St John's Wort + TacrolimusAnyone on tacrolimus should not start St John's Wort, and should tell the transplant team if they already have.
- St John's Wort + WarfarinTell the anticoagulation clinic before starting or stopping St John's Wort, so the INR is checked on a tighter schedule through the change rather than at the usual interval.
They work against each other5
- Acetaminophen (Paracetamol) + N-Acetylcysteine (NAC)After a suspected overdose, call a poison centre or go to hospital straight away rather than waiting to see how you feel.
- Metformin + Vitamin B12If you have been on metformin for years, this is a reason to have B12 checked, and to ask for methylmalonic acid rather than accept a normal serum B12 as reassurance.
- Testosterone + Human Chorionic Gonadotropin (hCG)Nothing here for a reader to act on alone.
- Zinc + CopperNothing changes for anyone getting zinc from food, or taking a multivitamin, or using lozenges for the few days of a cold.
- Zinc + IronNothing changes for most people, and this is not a reason to avoid a multivitamin, where the doses of both are small.
One boosts the other5
- Acetaminophen (Paracetamol) + NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)Taking the two together is reasonable for short-term pain, and the doses that work are lower than the maximum of either.
- Myo-inositol + MetforminIf metformin is working and tolerable, the evidence does not support trading it for inositol.
- Soy Isoflavones + Equol (S-equol)Nothing to do.
- Vitamin C + GlutathioneNothing changes for most people.
- Vitamin C + IronThere is nothing to buy here and, for most people, nothing to change.
No real interaction10
- Branched-Chain Amino Acids (BCAAs) + Dietary ProteinNothing changes.
- Branched-Chain Amino Acids (BCAAs) + Whey ProteinNothing changes for anyone already taking whey or eating enough protein.
- Creatine + Dietary ProteinNothing changes.
- Electrolyte Supplements and Sports Drinks + Alcohol (Ethanol)Nothing changes.
- Glucosamine + Chondroitin SulfateNothing changes.
- Lion's Mane (Hericium erinaceus) + WarfarinNothing changes for most people.
- Myo-inositol + D-chiro-inositolNothing changes if you already take myo-inositol.
- NMN (Nicotinamide Mononucleotide) + Nicotinamide Riboside (NR)Nothing supports paying for both.
- Soy Isoflavones + TestosteroneNothing changes.
- Vitamin D3 (Cholecalciferol) + Omega-3 Fatty Acids (EPA/DHA)Nothing changes.