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Synthroid 75 mcg is taken on an empty stomach, 30 to 60 minutes before breakfast
4 min readReviewed 21 August 2026. Updated
At a glance
Page typeNote
Featured strength75 mcg
Timing30–60 min before breakfast
ReviewerCamille Rousseau, MD
Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. SYNTHROID should be taken at least 4 hours apart from drugs that are known to interfere with its absorption.
01How the 75 mcg tablet is swallowed
Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. Levothyroxine absorption is increased on an empty stomach. A 75 mcg SYNTHROID tablet is taken as that single daily dose. SYNTHROID should be taken at least 4 hours apart from drugs that are known to interfere with its absorption.
In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dose. The peak therapeutic effect of a given dose of SYNTHROID may not be attained for 4 to 6 weeks. On a stable replacement dose, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient's clinical status.
How to cite this page - Vancouver style
Halo Medix Medicines Reference. Synthroid 75 mcg is taken on an empty stomach, 30 to 60 minutes before breakfast [Internet]. Montreal: Halo Medix; 21 August 2026 [cited 2026 Aug 21]. Available from: https://halomedix.com/notes/synthroid-empty-stomach/
('Readers around Montreal asked about the empty-stomach 75 mcg swallow. ', 'Answers follow the U.S. Synthroid label.')
Monique Lefebvre, Outremont asks
Can I take 75 mcg Synthroid with breakfast coffee?
Reply from our reviewer
Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. Coffee with breakfast sits after that wait. Grapefruit juice may delay absorption and reduce bioavailability. Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind levothyroxine and reduce absorption. This note features 75 mcg. The prescriber names the tablet.
Karine Bouchard, Longueuil asks
I take a calcium tablet. When does 75 mcg go?
Reply from our reviewer
Administer SYNTHROID at least 4 hours before or after drugs that are known to interfere with absorption. Calcium carbonate is on that list. Ferrous sulfate and some bile acid sequestrants also reduce levothyroxine absorption. The labelled gap is at least 4 hours. Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast.
David Chen, Saint-Laurent asks
Can I use 75 mcg Synthroid to lose weight?
Reply from our reviewer
Do not use SYNTHROID for the treatment of obesity or for weight loss. Doses within the range of daily hormonal requirements are ineffective for weight reduction. SYNTHROID is indicated as replacement therapy in primary, secondary, and tertiary hypothyroidism. SYNTHROID is not indicated for suppression of benign thyroid nodules.
Isabelle Gagnon, Westmount asks
If I miss the morning empty-stomach hour, do I double 75 mcg at night?
Reply from our reviewer
Administer SYNTHROID as a single daily dose. Do not take two tablets to make up a missed morning swallow unless the prescriber writes that instruction.
Claire Bensalem, Pointe-Claire asks
Which tablet strengths sit on the Synthroid row?
Reply from our reviewer
SYNTHROID tablets for oral administration are supplied as 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg, and 300 mcg. This note features 75 mcg. Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. Administer SYNTHROID at least 4 hours before or after drugs that are known to interfere with absorption. SYNTHROID is indicated as replacement therapy in primary, secondary, and tertiary hypothyroidism.
Yanick El-Khatib, Laval asks
Does iron sit on the same 4-hour gap as calcium?
Reply from our reviewer
Administer SYNTHROID at least 4 hours before or after drugs that are known to interfere with absorption. Ferrous sulfate reduces levothyroxine absorption. Calcium carbonate reduces levothyroxine absorption. Some bile acid sequestrants also reduce levothyroxine absorption. The labelled gap is at least 4 hours. Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast.
Sophie Traoré, Saint-Michel asks
Is 75 mcg Synthroid indicated to shrink a benign nodule?
Reply from our reviewer
SYNTHROID is not indicated for suppression of benign thyroid nodules or for weight loss. SYNTHROID is indicated as replacement therapy in primary, secondary, and tertiary hypothyroidism. Do not use SYNTHROID for the treatment of obesity or for weight loss. Doses within the range of daily hormonal requirements are ineffective for weight reduction.
Hélène El-Khatib, NDG asks
What half-life range is written for T4?
Reply from our reviewer
The prescribing information gives a T4 half-life of 6 to 7 days in the usual state, 3 to 4 days in hyperthyroidism, and 9 to 10 days in hypothyroidism. Absorption of oral T4 runs 40% to 80%, mostly from the jejunum and upper ileum. Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. This note features 75 mcg. T4 is more than 99% bound to plasma proteins.
Lucie Fortin, Pointe-Claire asks
Can biotin change a TSH print after a 75 mcg swallow?
Reply from our reviewer
Biotin supplements can interfere with immunoassays for TSH, T4, and T3. Stop biotin and biotin-containing supplements for at least 2 days before the draw. Assess TSH 6 to 8 weeks after initiation or a change in SYNTHROID dose. Peak therapeutic effect may not be attained for 4 to 6 weeks. This note features 75 mcg. Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. This note features 75 mcg. Peak therapeutic effect may not be attained for 4 to 6 weeks.
