Supplement guides
Practical answers about choosing, buying and taking supplements in the US.
Supplements you shouldn't take togetherWhich supplements shouldn't be taken together? Risky drug combos, doubling up past daily limits, and pairs like iron and calcium that just need spacing.Read →When to take your supplements: morning, night, with food or on an empty stomachWhen to take 24 common supplements, from vitamin D and magnesium to iron and probiotics: morning or night, with food or not, plus pairs to space apart.Read →Sending supplements to family in South Korea — customs limits, shipping options and what to pickSending vitamins to family in South Korea? The 6-bottle and US$150 duty-free limits, the PCCC customs number, banned ingredients and how to ship them.Read →How to save on supplements this Black Friday and Cyber Monday (2026)Black Friday 2026 is Nov 27, Cyber Monday Nov 30. How to spot real supplement deals: cost per serving, expiration dates, how much to stock, FSA and fakes.Read →Korean-style supplements in the US: what to look for on the labelWant Korean red ginseng, milk thistle, probiotics or lutein in the US? How to match Korean standards to US Supplement Facts labels before you buy.Read →How to read a Supplement Facts labelHow to read a Supplement Facts label: serving size, %DV, elemental magnesium, EPA + DHA, units (mcg, IU, DFE, RAE, CFU), blends and USP/NSF seals.Read →Where should you buy supplements? Costco, Amazon, iHerb, Walmart and Target comparedWhere to buy vitamins and supplements in the US: Costco, Amazon, iHerb, Walmart, Target, CVS and brand sites compared, plus how to avoid fakes and HSA/FSA tips.Read →Can you use your HSA or FSA to buy supplements?Can you buy vitamins and supplements with an HSA or FSA? Most don't qualify under IRS rules. When a Letter of Medical Necessity works and the tax risks.Read →