Beta blockers

Any info on how beta blockers affect thyroxine t3 / t4?

I used to be on them for anxiety for years.

I'm now not taking them and had issues trying to get thyroid levels right due to sertaline (no one realised it was affecting it) and low ferritin. IVe actually had thyrotoxicosis I now believe as we were trying to correct things.

I used to be on 125/150 alternate days with beta blockers. Im now on this again however wondering if perhaps it's still too much.

My gp is being very strict about waiting 3 months before testing which I do agree with however this info could help make decisions to check sooner. My ferritin is now good and I don't experience the anaemic fatigue however I'm struggling to gain muscle and in a lot of pain due to hypermobility syndrime - though I'm pretty sure the syndrome part has been exacerbated by the thyroxine issues, hypo then hyper.

I just found a line "affects conversion to t3" on a pharmaceutical website.

12 Replies

  • Ferritin was never previously looked nor hms at so issues in the past could have been due to this than my hypothyroidism, clearly I'm worried about bone density!

  • Hi If on beta Blockers never take them on the day of the thyroid test until afterwards as they give a false thyroid result.


  • I have also seen somewhere that beta blockers can reduce effect of t4 ,possibly the conversion to T3. I had angina as soon as started on T4 , a very low dose of beta blockers controls the angina. Conversion does not seem a problem for me t3 is high but still have symptoms so having a brain scan.

  • Beta blockers are contra - indicated because they negate the effect of thyroxine completely.

  • This is what ive now realised - although at least for quite some time I was happily on a daily slow release with 125/150 thyroxine.

    What I'm trying to ascertain is potentially what difference it might have made to how I felt - it seems it affects comversion t4 to t3, this would suggest that it would affect the t3 outcome in test but I suspect not much on Tsh as it would take longer to react.

    And therefore should I perhaps try going to 125.

    I think I'm still experiencing very difficult hyper effects, and ive probably been on too much for several months now.

    However it's only been two weeks since I dropped from 150 to 125/150.

    I guess I could try two 150s each week and the rest 125 and not discuss with gp.

    I'm getting while body attacks still where my muscles get very tight. Not sleeping much, bit sweaty and very achey. Lost some weight again. Weak.

  • I guess I mean - what percentage changes have been seen in results when taking propanolol. I can't find any papers.

  • I would have thought the symptoms would be that the T3 was negated and under active symptoms would return with a vengeance!

  • In a Mercury pharma leaflet "propanalol may decrease the peripheral conversion of levothyroxine to t3"

    But I'd really like to see some data?!

  • Glynisrose it must have been simply a reduction in t3 when I was on propanolol. I had to raise from 125 to alternate days with 150. When I then got fit I was great.

    I don't want to be on propanolol ideally; only in emergencies.

    So I guess maybe I should be on 125. Obviously any drop always makes me hesitate!

  • To clarify I came off propanolol to get pregnant so obviously the dose then was very different.

  • Every paper States simply may reduce conversion. It must have been through yellow card or something.

  • I have now found more info: it increases rt3 and so reduces t3.

You may also like...