Thyroid UK
84,009 members98,997 posts

Has anyone experienced Hypothyroidism whilst taking antibiotics (specifically Trimethoprim or ceflaxin)?

I have had Hasimotos for over 10 years and never experienced any symptoms, happily remaining stable on 150mg levothyroxine. In the last year my TSH went from 1.8 to 2.6 to 3.8, my doctor wasn't concerned as I was within range 0.7-5 and didn't change my dose.

Shortly after the last blood test, I got a bladder infection and took trimethoprim for 3 days and then ceflaxin for 6 days. During these 9/10 days I went rapidly downhill, from feeling completely fine (with a bladder infection) to breathless and tired after a couple of days and the aches and pains all over my body, headache, fatigue, feeling cold, really breathless, eye sight deteriorating and unable to concentrate, dry skin - textbook hypo! My TSH is now 5.8 (normal T4 of about 17) which doesn't seem that high to me for these symptoms to be so severe. Doctor is trying me on 175mg for a few days to see what happens. I can't believe how quickly this happened and am wondering if the antibiotics could have had anything to do with it (I know that ciprofloxacin stops Levothyroxine absorption).

After 10 years with the disease I am shocked at how terrible it can make you feel and feel so much for those that experience these symptoms over long periods of time and can't convince their doctors to treat them with a TSH of under 10! This happened to me at just above TSH 5, my doctor thinks 'I am sensitive'!

Anyone hear or experience anything similar with antibios?

11 Replies

After being Diagnosed with thyroid cancer a 2 years ago and been operated last year I was prescribed 150mg of thyroxine because my cancer cells were still there. Being on a high dose of thyroxine is causing me to have symptoms of hypothyroidism even if I don't have a thyroid. Lol.


What's your TSH, T4 and T3? Sounds like they haven't got your levels perfect yet


Last time they so me was in April. My Thyroglobulin 1.7, T4 is 4.8 pm0l and T4 23.6. TSH is 0.05mu/L. My cancer was also in 42 Lymph nodes and they had to remove 84. Plus in both lymph glands. When I so the Lupus doctor he did the thyroid function tests also and in there it shows that I have too much thyroid hormones and that means my thyroid is working too much causing me wait loss. They said They cannot reduce my dosage until the cancer cells are gone. My next thyroid checkup is in December.


Good luck with it Puneet


Hi N. I can't do better than speculate, but maybe as you suggest some sort of disruption of gut function leading to reduced absorbtion is a possibility. Might it be possible too that disruption of this sort and or response to the antibiotics could have kicked off some sort of wider immune response? Leading to some alteration in the conversion, deactivation (conversion to reverse T3) of thyroid hormone?

Increased stress (maybe caused by the infection, or by something else) resulting in high cortisol levels can seemingly have this sort of effect too.

You got a very speedy response, and while others may know different there doesn't seem to be any commonly reported short term link (that i've seen anyway) between antibiotics and thyroid or other metabolic functions.

Against that it is widely held that antibiotics can longer term lead to gut problems, and subsequent immune responses and thyroid disease as a result of killing off bugs/altering the balance of gut flora, and by generally upsetting the gut. The suggestion seems possibly to be that the resulting inflammatory and absorbtion issues may normally take longer to manifest by causing mineral deficiencies, and immune responses.

Your TSH seems anyway quite high at 5.8. There are plenty of doctors that would regard that as normal, and indeed some may feel OK at that - but there's equally plenty here reporting that they need to be well below 1 to feel right. (myself included) That 5.8 would ensure hypo hell. There's also those of us that don't get on with T4 on its own no matter how much we take. This description by a US doc of his treatment approach seems to fit well with what many of us have experienced regarding TSH and blood hormone levels:

Wonder if it's possible that the antibiotic by messing even a little with your use of thyroid hormone might with the added stress of illness have tipped you over the edge? Bladder (and sinus) infections can (or might not) be indicators of hypothyroidism. Or maybe that something coincidental (less likely) happened?

I'm very wary indeed of antibiotics, and don't touch the things except in extreme need and short term. I was treated long term with strong antibiotics many years ago by an unknowing doctor for a chronic sinus infection that with fatigue was in retrospect probably the first evidence of my developing metabolic problems. (the fatigue was probably my adrenals shutting down/scaling back in response to chronic stress) I'm pretty sure that they played a large part in causing/exacerbating the long running gut and immune issues i developed. Which ran on into long undiagnosed hypothyroidism and thyroid auto immune disease - and a thyroidectomy for a thyroid cancer..



Hi Nathalina, In 1978 I had a sub-total thyroidectomy while 14 weeks pregnant with my daughter (3rd child). Was not treated at all but began to have symptoms of being hypo when my daughter was 5 months old. At this time I also had a urine infection and was treated with Septrin. From then until 1997 when I was started on Thyroxine I had terrible symptoms of being hypo. About 4 months after starting T4 I began to feel better. Felt quite good for a few years until September 2007 when I was given Trimethoprim for another urine infection and to date am still suffering from the most awful hypo symptoms. Aches and pains have improved a bit with supplementation of Vit D3 and B12, B-Complex and Nutri-Adrenal, but my skin, which had broken out in awful spots, mostly on my scalp which is very sore, has not really improved at all and I am feeling colder by the day at the moment. I felt I was improving until about 6 months ago, but believe there could be problems with T4 tablets. Although all my thyroid bloods look good on paper - TSH 1.27 (0.30 - 3.50?), FT4 14.2 (6.00 - 14.00) and FT3 5.6 (3.1 - 6.8) this doesn't tell the true story of how I feel. It has been mentioned on this forum that we shouldn't have Sulphonamides, of which Trimethoprim is one, but I don't think most GP's or Consultants pay much attention to this. I also was given Tetralysal in 2009 to counteract the spots from Trimethoprim, which only made matters worse. Needless to say the medical profession are denying antibiotics have anything to do with my symptoms and are just turning a blind eye. Let me know if you have any luck with your GP treating you differently. Wish you well, Janet.


Thanks Janet. Will check out the Sulphonamides link. What has become clear to me from this forum is I have been slightly hypo for some years with TSH over 1.85 and increasing. My doc though this was perfect but I am carrying too much weight and been experiencing joint pains and feeling tired for years, but just thinking this is normal!


if you have an infection anti-biotics cause a die off reaction which is where toxins from the dying bacteria are released into your body ad make you feel very poorly. A die off reaction shows you have an infection. I I have read somewhere that lyme disease cause gallbladder infections. Have you ever been tested fr Lymed disease?

Best Wishes-Gimi-energy.


Ok I have scoured the Internet for any contra-indications between Antibiotics and Levothyroxine. There is no real evidence from drugs tests or doctors apart from a British Medical Journal article about Ciprofloxacin. HOWEVER it seems the vetinary world is very aware of a link and mentions Trimethrapim in a few articles as lowering Levothyroxine absorption. This article seems helpful:

several medications may alter the results of thyroid function tests in dogs. Here are the major culprits:

Sulfonamides alter thyroid function early during antibiotic therapy

• < one week of therapy in some cases

• Can lead to clinical hypothyroidism, where thyroid testing cannot distinguish true hypothyroidism from iatrogenic (DO NOT TREAT)

• Signs and abnormal function tests gradually resolve once sulfonamide treatment is withdrawn

• Minimum withdrawal before testing is four weeks

• Some patients require up to 12 weeks to return to euthyroidism

Glucocorticoids alter thyroid function in a dose and time dependent manner

• The longer the duration of therapy, the longer the duration of suppression

• Can lead to clinical hypothyroidism (iatrogenic) (DO NOT TREAT)

• Best to withdraw a minimum of three weeks for short-term oral administration • Adjust withdrawal period based on dose, duration, and route of therapy

• Repositol steroid administration can effect thyroid function for months

Phenobarbital administration can result in an inability to accurately diagnose hypothyroidism

• Decreased thyroid function testing can be observed within three to five weeks

• Function normalizes after four weeks of withdrawal, if appropriate

• If cessation is inappropriate, a trial of levothyroxine is warranted if clinical signs and thyroid function tests are compatible with a diagnosis of hypothyroidism

These are the sources: - "drugs that may influence thyroid function – corticosteroids, phenobarbital, potentiated sulfonamides, dietary soy or soy phytoestrogens, insulin, narcotic analgesics, salicylates, tricyclic antidepressants, furosemide, phenylbutazone and mitotane (Dodds, 1995 and 1997)"


This is the BMJ study on Ciprofloxacin


Hi. I have had sinus problems and ibs and then had glue ear. It became infected and painful so was put on antibiotics which I sprayed into the ear. It eventually cleared it but but straight away I noticed that I then got a sort of tender neck around the back of the neck and sometimes under the ears, which will not shift.

I also get days were I feel freezing cold even if in a warm room in lots of clothes. Yet then for a month that is fine and then another day where I feel freezing cold. Headhces, lots of wheezing and coughing.

My doctors do not seem to be much good at putting things together and looking at the whole picture or using common sense. So if you say to them you have a bad cough they suggest honey or cough syrup rather than seeing it is a symptom or part of something or needs to be diagnosed.


You may also like...