1 doctor weighed in:
How long should it take Synthroid (thyroxine) to start working?
1 doctor weighed in

Dr. Richard Shewbridge
Internal Medicine - Endocrinology
In brief: 2-5 days.
Synthroid (levothyroxine) has a very long half-life.
Levels start to rise in a few days, but take 5-6 weeks to reach a plateau.

In brief: 2-5 days.
Synthroid (levothyroxine) has a very long half-life.
Levels start to rise in a few days, but take 5-6 weeks to reach a plateau.
Dr. Richard Shewbridge
Dr. Richard Shewbridge
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