Thyroid UK
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Reintroducing T4 with T3

I've been taking T3 only for over a year and have got on pretty well with it. However, I'd now like to experiment with reintroducing a little T4. I'm wondering exactly how to go about that in terms of dosages.

I'm currently taking 50mcg T3: 25 on waking; 15 at 11.30; 10 at 4pm.

I've been advised to take the T4 at bedtime to avoid competition with the T3 in the morning, so I took 12.5mcg T4 last night and intend to stay on the same T3 dose for several days and monitor vitals.

After that (and depending on effects), what then??? Reduce the T3? If so, which dose and by how much'? Or add in another 12.5mcg T4?

I'd be grateful for others' experiences and suggestions. Thanks.

3 Replies

Coppernob, There's no need to take T4 and T3 apart, they don't 'compete'. Most people take one dose of T4+T3 together and the 2nd dose T3 only.

You don't need to titrate T4 either. I was switched from 60mcg T3 to 200mcg T4.

If you want a reasonable level of FT4 you'll need to take more T4 than T3. 50mcg T3 is equivalent to 150mcg T4. Maybe try 75mcg T4 with 25mcg T3? While T4 is being absorbed keep on 50mcg T3 for 5 days, reduce to 37.5mcg day 6 and 25mcg day 7.

1 like

Thanks. Interesting.

I'm not actually that bothered about absolute levels of FT4 or anything else (within reasonable limits!). I'm more concerned with how I feel, and my vitals, which I'll monitor regularly.


Coppernob, you can reduce T3 by 6.25mcg for every 18.75mcg T4 added (25mcg/12.5mcg alternate days) until you hit a sweet spot.


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