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About this tool
Check the gaps between your levothyroxine dose and coffee, breakfast, calcium, iron and antacids.
The Thyroid Medication Timing Planner measures the gap between your levothyroxine tablet and everything that blocks its absorption, then tells you which gaps are long enough. It applies the separations in the product labelling and the trials behind them: at least 30 minutes before food (60 is better), 60 minutes from coffee, 4 hours from calcium, iron, antacids, proton-pump inhibitors, soy and high-fibre meals, and 3 hours after the last meal if you dose at bedtime. Useful for anyone whose TSH keeps drifting despite taking the same dose every day.
Open Thyroid Medication Timing Planner on AltFTool — it loads instantly in your browser.
Choose Morning, before breakfast or Bedtime, set the Levothyroxine tablet at time, then enter clock times for Breakfast / first food, Coffee or espresso, Calcium supplement or antacid and Iron / multivitamin with iron — leave blank anything that does not apply.
Each row under Gap by gap shows the real gap against the one it needs — 30 minutes before food (60 preferred), 60 minutes from coffee, 4 hours from calcium, iron, antacids and fibre — and names the clock time to shift to when it falls short.
The Routine check headline reads All gaps clear or how many gaps are too short, with Suggested tablet time and Biggest shortfall listed below and Your day in order marking each event Dose, Clear or Too close; Copy result copies the whole check.
Checks food, coffee, calcium, iron, acid drugs and fibre against their own separation, not one blanket rule.
When a gap is short it names the exact clock time to move the tablet or the item to.
Handles overnight dosing, including times that cross midnight, using the 3-hour post-meal rule.
At least 30 minutes, and 60 minutes gives more consistent absorption. Food roughly halves the fraction of the dose that reaches the blood, which is why the tablet is taken with water on an empty stomach.
60 minutes. A 2008 study in Thyroid showed espresso taken with or shortly after the tablet significantly reduced absorption, and the effect persisted even without milk, so black coffee is not a workaround.
Four hours. Calcium carbonate and ferrous sulfate bind levothyroxine into complexes the gut cannot absorb, so most people put the tablet in the morning and the supplement at lunch or later.
Both work if you are consistent. A randomised crossover trial published in 2010 found bedtime dosing produced slightly lower TSH than morning dosing, probably because an empty overnight stomach is easier to achieve — but it only works if your last meal was at least 3 hours earlier. Discuss any switch with your doctor and have TSH retested about six weeks later.