How long to space supplements from medications
Some supplements need to be taken hours apart from certain medicines so they don't block absorption. This page covers the common ones — it is about timing, not treatment, and it is never a personal safe-or-unsafe verdict. Your pharmacist can check timing and safety against your exact prescriptions.
⚠️ Never start, stop, or change a prescribed medication based on this page. No supplement here treats or replaces a medication. When in doubt, ask the prescriber or pharmacist.
⏱️ Space these apart (absorption)
Clock-based timing — take the supplement and the medicine hours apart.
Levothyroxine (thyroid)
Take once daily on an empty stomach, 30-60 minutes before breakfast. Keep calcium and iron at least 4 hours away, and separate coffee or tea by about 30-60 minutes.
Don't: Don't self-adjust the dose, and no supplement treats or replaces thyroid medication.
Source: MedlinePlus — Levothyroxine
Antibiotics — tetracyclines & fluoroquinolones (e.g. ciprofloxacin)
Minerals bind these antibiotics and block absorption — the exact gap differs by drug. For ciprofloxacin, take it at least 2 hours before or 6 hours after calcium, iron, zinc, magnesium, or a multivitamin. For tetracycline, iron 4 hours before / 2 hours after, and calcium/antacids 6 hours before / 2 hours after.
Don't: Don't assume one gap fits every antibiotic, and spacing only protects absorption — it isn't a safety clearance.
Source: MedlinePlus — Ciprofloxacin
Bisphosphonates (e.g. alendronate) for bones
Take just after getting up on an empty stomach with a full glass of plain water, then take nothing else — including calcium, vitamins, or antacids — and stay upright for at least 30 minutes.
Don't: Calcium and vitamin D don't replace the medication; they're taken later in the day, not together.
Source: MedlinePlus — Alendronate
🩺 Monitor these (nutrient levels over time)
Not a timing trick — these are long-term absorption effects worth raising with your doctor, who may check a level.
Statins + CoQ10
Statins can lower the body's CoQ10 levels. Whether CoQ10 supplements relieve statin-related muscle aches is not proven — trials conflict — so it's a question for the prescriber, not a self-treatment or a reason to stop a statin.
Don't: Don't stop or change a statin, and don't treat CoQ10 as a proven fix for muscle symptoms.
Metformin + vitamin B12
Long-term metformin can lower vitamin B12 levels. This is a monitoring point — worth asking your doctor whether your B12 should be checked — not a timing rule.
Don't: Don't self-start B12 to 'cancel out' metformin or change your diabetes plan on your own.
Source: NIH ODS — Vitamin B12
Acid reducers (PPIs) + B12 / magnesium / iron
Long-term PPI use can reduce absorption of B12, magnesium, and iron. The FDA advises checking magnesium before and during prolonged use. Again, a monitoring conversation with your doctor, not a spacing trick.
Don't: Don't stop a PPI on your own, and supplements don't simply offset the effect.
Source: NIH ODS — Magnesium
Warfarin + vitamin K
The goal is a consistent vitamin K intake — sudden changes (from food or a supplement) can shift how warfarin works. Keep intake steady and tell your anticoagulation clinic before changing supplements or diet.
Don't: Don't try to eliminate vitamin K, and don't start or stop a K supplement without your clinic.
Source: NIH ODS — Vitamin K
Keep your list in one place
The simplest way to get timing right is to see everything together. The planner lets you export a clean list to bring to a pharmacist, and the compatibility chart covers supplement-to-supplement spacing. For anticoagulants specifically, see supplements & blood thinners.
Common questions
How long after taking levothyroxine can I take other supplements?
Take levothyroxine on an empty stomach 30-60 minutes before breakfast, and keep calcium and iron at least 4 hours away. Coffee and tea are best separated by about 30-60 minutes. Other supplements can usually go with a later meal — but confirm the specifics with your pharmacist.
Which supplements interfere with antibiotics?
Calcium, iron, zinc, and magnesium (and multivitamins/antacids that contain them) can bind tetracycline and fluoroquinolone antibiotics and reduce absorption. The exact gap differs by antibiotic — for ciprofloxacin it's at least 2 hours before or 6 hours after. Always check your specific antibiotic's leaflet or ask the pharmacist.
Is it a spacing problem or a monitoring problem?
Two different things. Levothyroxine, antibiotics, and bisphosphonates are about clock-based spacing for absorption. Statins/CoQ10, metformin/B12, and PPIs are about long-term nutrient levels — a monitoring conversation with your doctor, not a timing hack. Warfarin is about keeping vitamin K intake steady.