accidental overdose of thyroxine

[Tjqui00]

I’m on 100 mcg thyroxine and the kart prescription they only had 25 mcg so I was taking 4 tablets a day and then the recent prescription was 100 mcg. I’ve just realised today that I’ve been taking 4 100 mcg a day I think for 4 days from how many are gone. In a bit of a panic. I’ve rang 111 and they called back and are getting me an out of hours appointment today and I’m waiting for a call back.

I had a thyroid test done yesterday as well and that’s gone to be invalid now. Hope the doctor ignores that test.

[helvella]

If you are not feeling horribly over-dosed, relax. That is, if you don't have a high heart rate, possibly sweating/feeling hot or other significant symptoms.

We have had many who have taken too much. Doing so for a few days, it has little effect.

Testing levothyroxine tablets, they typically give a dose of 600 micrograms - to people who don't need any!

You might skip your next dose, or two. Depending on how you feel.

It is unfortunate that you had a test, I agree.

[Tjqui00 in reply to helvella]

Thank you for your reply. I haven’t taken any today. I have been feeling a bit hotter than usual, but hard to tell as I’m menopausal. I’ve had a throbbing pain in my neck on and off for a few days so wondering if that’s related and irritated eyes with crust in them and a bit blood shot, which I thought was conjunctivitis. My heart rate and blood pressure is ok at the moment.

I was having a blood test because the doctor wants to reduce my dose and I wanted my FT3 tested before I did. Hope the doctor ignores that test and lets me retest again. Not sure how long I should leave it now before being tested again.

[helvella in reply to Tjqui00]

I suspect by the time you talk to anyone from 111, you might be feeling better. And add onto that, the only thing they are likely to do is give you a beta-blocker (propranolol), and that will probably take at least another day to get to you!

One thing, the peak impact of T4 can be two or three days after taking the dose.

In serious overdoses, like dozens and dozens of tablets, this is sometime missed, and the patient sent home, then has to be re-admitted.

Therefore, think carefully before re-starting. You could feel better for a few hours, then worse again. Unlikely to be dramatic!

[Tjqui00 in reply to helvella]

111 have called back and are arranging a face to face appointment for me today. Haven’t had a call back for that yet. Do you think I could still get symptoms and when do you think I should start taking thyroxine again? I haven’t taken any today.

[helvella in reply to Tjqui00]

You could get continuing symptoms but I am no expert in levothyroxine overdosing!

I think you need to see how it goes. But don't rush return to your usual dose.

You are obviously not currently putting any more levothyroxine into your system. So that will already be dropping.

The reason symptoms continue is that you are converting the T4, which we can assume is rather high, into T3. That is delayed, because that is how our bodies work.

As a matter of guesswork, you could expect the peak of T3 (hence the peak impact) at 48 hours after taking your last dose. But you could already be past the peak.

[SlowDragon Administrator]

Work out how many days you have taken 400mcg instead of 100mcg

If 4 days thats 4 x 300mcg extra per day

Skip next 3-4 days completely

Then perhaps start back at half a tablet (50mcg) before going back to 100mcg daily after about a week

Retest in 6-8 weeks

[Tjqui00 in reply to SlowDragon]

I thought just skipping a few days would be enough and then go back on my usual dose.

I’m waiting for a call back for a face to face appointment today. Not sure I need to be seen. Assume they’ll check my heart, pulse and blood pressure. I’ve checked my blood pressure and pulse today.

[Heloise]

At one time it was thought you could take one week's prescription on one day per week. I don't think it's a good idea even though it is a storage hormone which has to be converted before the body uses it. So, you took 1600 mcgs? That is more than two weeks rather than the 700 mcgs. which might have been permissible. This was only recommended for thyroxine T4 and not anything containing T3. Unless it has changed the half life of T4 is about two weeks so consider that, but I'm sure there are other variables that might apply.

[Tjqui00 in reply to Heloise]

Yes I would have taken 1600 mcg over 4 days instead of 400 mcg. Don’t like the idea of not taking anymore for 2 weeks though.

[Heloise]

I agree and didn't mean to imply that. It was just information. Follow hellvella's advice. Your body may tell you how to proceed.

[Tjqui00]

doctor called back and thinks it should be fine. He thinks I should skip 4 days and then go back to my usual dose, but ask my doctor on Monday. He asked if I had an Apple Watch and could do an ecg reading. My husband does, so I did it while on the phone and showed no atrial fibrillation. Said to test a few times a day and check blood pressure over the next few days.

[helvella in reply to Tjqui00]

Good!

I wish I'd thought to suggest an Apple Watch - that was a good idea.

[waveylines]

Glad you've got a plan. It's so easily done tbh.....especially as we often take out thyroid tablets first thing on waking. If your doctor has any sense he will retest in a few weeks time when your over this extra boost you've given yourself!!

[Tjqui00 in reply to waveylines]

thanks. Will call mr doctor tomorrow morning and hope they ignore that test. I’d still like to know what the result is though.

[waveylines in reply to Tjqui00]

They should do and infact they should leave it a few weeks to let things settle. You could always message via NHS app as it then creates a record on your file.

[Otto11]

Glad you’ve got a plan in place. It’s so easy done. My daughter did exactly the same but with a different medication.

[Tjqui00 in reply to Otto11]

I do feel annoyed with myself! My husband was really angry with me and said I can’t be trusted, but I’ve never done anything like that before. I’ve missed an odd day a few times before but never overdosed.

[Otto11 in reply to Tjqui00]

At least it was only 4 days. Like I say easy done.

[Tjqui00 in reply to Otto11]

Double the dose would be bad enough, but it was 4 times my dose! Wouldn’t have been as bad if I was on a lower dose like 25 or 50 mcg. It’s just knowing when to start back on them.

[Otto11 in reply to Tjqui00]

Don't beat yourself up. In my daughters case her usual prescription was for 20mgs Esomeprazole x 4 daily. without realising as the packet is exactly the same the Pharmacy sent 40mg tablets. She continued for months taking 160mgs daily till she realised (although I don't understand how the pharmacy gave her son many). The outcome is she no longer absorbs medication properly as very low stomach acid. she has Vit D & B12 injections & Ferritin infusions regularly. She still hasn't managed to reduce the dose as every time she tries it makes her ill. Your Dr will guide you . Take care.

[Tjqui00 in reply to Otto11]

That sounds awful. Sounds like it’s the pharmacy’s fault.

[Otto11 in reply to Tjqui00]

50/50 I guess.

[mrskiki in reply to Tjqui00]

Perhaps the anger was more of a sort of panic reaction due to worry xxx

[1tuppence]

I did something similar due to changes in brand. I thought I was taking 125mcg, but in fact was taking 200mcg. This was for 10 days before the penny dropped. I had a regular NHS Thyroid blood test. I felt wonderful...full of energy and Life. My T3 went to 5.3....best it has ever been. T4 was well over-range. When I realised what I'd been doing, I immediately reverted back to 125mcg.

[Tjqui00]

I’ve had my results back from the blood test Friday and my FT4 is 31 (range 7.9-14) and FT3 7.2 (range 3.8-6). FT4 was 17 last test and this one was to see if I needed to reduce my dose and see what the FT3 was. Assume it’s so high because of 3 days previously taking 400 mcg a day instead of 100.

[helvella in reply to Tjqui00]

Thanks for adding that.

How are you feeling?

When you do decide you have stabilised and it is time to consider a dose adjustment, and assuming FT4 is approximately 17 again, do consider that a very small reduction might be sufficient. For example, 87.5 (by alternating 100 and 75, or 50+25+half a 25) might make a big enough difference.

Doctors have a strong tendency to make heavy-handed adjustments - like from 100 to 75 - when small adjustments, made slowly, should ensure you close in on a good dose rather than go way past and have to raise it again.

[Tjqui00 in reply to helvella]

I feel fine and don’t have any hyper symptoms. Still not sure when to go back on my dose. Was wondering whether to take it tomorrow but whether skipping 3 days is enough, I spoke to a pharmacy technician today who was meant to speak to a doctor about what to do and call me back, but she hasn’t yet. She said maybe don’t take any for a week and have another blood test in a week, but I don’t agree with that. I think I should wait a month before re testing, or a few weeks. Also, don’t want to wait a week before going back on them.

[helvella in reply to Tjqui00]

I think you are in an impossible situation. What you need is something like twice a day testing to see how the levels are changing. If only that were feasible!

It is all very well using arithmetic to add up what you have taken and trying to work it out. But I think that your rate of excretion will be different to "normal" - faster. And there simply is no proper research into such things. (It is difficult to see how they could do that, of course, but it still ends up that not enough guidance is available.)

It's probably a very bad idea to allow yourself to dip into being under-dosed.

Maybe, when you decide is time, restart with a 50 microgram dose and see if you notice it?

[Tjqui00 in reply to helvella]

Do you think it’s too soon to start back on my usual dose of 100 tomorrow after skipping 3 days?

[helvella in reply to Tjqui00]

Well, I think I would be more cautious than that.

But I've never been in anything like your situation.

If your FT4 is still somewhat high, taking your normal dose will tend to keep it high. Taking 50 would allow it to still fall, but more slowly.

[Tjqui00 in reply to helvella]

The test was done on Friday morning. I did take 4 x 100 mcg after my blood test (actually it might have been 3 because Saturday morning I noticed 1 left from the day before). I haven’t take any more since then.

[Tjqui00]

doctor said to retest in 6 weeks and is refusing to do FT4 or FT3 and said they only test that if the TSH is abnormal. I had to fight to get the FT3 tested and it was finally tested this time by a different doctor and that result now needs to be ignored.