Thyroid UK

Heavy periods

Hi I've now been taking levo thyroxine for nearly 6 weeks and was hoping to get less heavy periods. Instead they tend to start a week earlier with spotting and I have a huge build up of stomach cramps. Then still really heavy & can't go out first 2 days. Maybe I need to wait until I've been on the medication a while longer or am I expecting too much. Definitely got more energy the rest of the time just not that week!

14 Replies

I hope you are taking iron supplements.


You actually need to be on the correct dose of levo for your body before ALL your hormones will settle down. This won't happen in 6 weeks as you will need dose increased every 6-8 weeks for maybe a year until your TSH is around 1 and your T4 and T3 are in the upper values of their ranges.

If you are heavy periods it is important you have your haemoglobin AND ferritin levels checked. You need to keep your haemoglobin over 12g/dl and ferritin half way in it's range. Please be aware the NHS adequate levels are different and will leave you mildly anaemic or iron deficient so you need to get the results from the doctor and/or get yourself tested then take action yourself as without optimal iron levels you will have more difficulty absorbing the levo.

Levo needs to be taken 4 hours away from iron supplements.

Oh I forgot to add your GP maybe difficult and refuse to test your iron levels because you have hypothyroidism so they can blame everything that. However they should be testing your vitamin D, folate, vitamin B12, ferritin and folate levels as those with hypothyroidism often have depleted levels as thyroid hormones effect your metabolism and absorption of nutrients. In the case of haemoglobin and ferritin as you have heavy periods you are in your rights to ask for a test everytime you have symptoms and signs of iron deficiency, however some GPs will refuse to do one or them both.


Thanks, that's really helpful. I do take iron tablets but wasn't aware of taking them 4 hours apart from the levo thyroxine. Yes I am hoping too much perhaps after 6 weeks!


Your GP should recheck your thyroid levels after 6-8 weeks. Quite likely that you will need to slowly increase dose. We usually need TSH towards lower end on range to feel improved when taking Levo. Body needs time to adjust, so steps up slowly and maximum increase of 25mcg at any one time and retesting at 6-8 weeeks after any dose change.

Usual advice on ALL thyroid tests, is to do early in morning, ideally before 9am. No food or drink beforehand (other than water) If you are taking Levo, then don't take it in 24 hours before (take straight after). This way your tests are always consistent, and it will show highest TSH, and as this is mainly all the medics decide dose on, best idea is to keep result as high as possible

Did your GP explain Levo should always be taken on an empty stomach and then nothing apart from water for at least an hour after. Many take on waking, but many of us prefer to take at bedtime. Can be easier/more convenient. There is research that shows taking at bedtime may also be more effective. (Can be equivalent to small increase in dose)

Long research article - final conclusion paragraph below

"In conclusion, bedtime intake of levothyroxine in our study significantly improved thyroid hormone levels. This may be explained by better gastrointestinal bioavailability at night or by less uptake interference by food or medications. As shown in this study, bedtime administration is more convenient for many patients. Clinicians should inform their patients about the possibility of taking levothyroxine at bedtime. A prolonged period of bedtime levothyroxine therapy may be required for a change in quality of life to occur."

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Wow - this is literally what happened to me too! (For a while, I was confused actually, if it was my post I was reading :)

As bluebug said, it is a matter of sufficient thyroid hormones; just wait, and it might (-probably will-) get better with time. Also my doctor said the same thing.

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Great advice especially about when to take it as I've been taking it first thing in the morning but pretty much just before breakfast as don't have enough of a gap as not an early riser. I think I should change it to taking the tablet just before bed.


Assuming you find taking at bedtime is good, you will need to get thyroid levels retested 6-8 weeks after.


If you can get your iron levels to optimal it will probably help to reduce your period problems - there are no guarantees though. Optimal iron levels help the body to make proper use of the thyroid hormone you are giving it with the Levo as well, so iron is really important.

If you want to pay for a full iron panel then you can do it privately, without involving your doctor, for £39.

You have to order a test kit, which will be sent to you through the post, then you have to follow the instructions you are provided with to prick your fingers to get a blood sample. The blood sample is sent back to the lab through the post, then results are sent to you via email.

To get an accurate result for iron testing it is advisable to stop taking all iron supplements for five days before getting your sample.

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The medichecks test doesn't include haemoglobin.

Though ideally a GP should be able to do a haemoglobin (sometimes called a haemoglobin estimate) for you either on it's on or part of a full blood count (or complete blood count).


Yes, sadly, nothing is perfect. But it is a lot better than getting just a ferritin from a doctor, which is what happens to many of us. :(


It has taken years for us to be 'finally' diagnosed but female problems could be at the top of the list of 'symptoms'.

Six weeks is a very short time to have much of an effect on your body overall as everything in our body is affected from head to toe. As long as your doctor increases your dose according to your symptoms and not stop increasing once your TSH is 'anywhere in range' you should gradually get back to 'normal'.

The aim for us is to have a TSH around 1 or lower. Doctors think anywhere in range is fine which isn't if we have symptoms.

You are now due a blood test at six weeks and to get the best results for you is:-

1. To have the test at the very earliest possible time and fasting.

2. Allow 24 hours between your last dose of levothyroxine and the test and take afterwards.

If you've not had your your antibodies tested ask for this as well as B12, Vit D, iron, ferritin and folate.

Always get a print-out of your results for your own records with the ranges and post if you have a query.

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I know as a child I always had to have extra vitamin B12 supplements & once when I was away in Italy they injected me with it as they knew I needed it. Is it true that even if I took extra iron tablets if I don't have enough vitamin B12 it will affect the absorption of the iron I'm taking? At my doctors quite reluctant to give me a print out which I wanted.


Under the Data Protection Act 1998 you have a right to copies of your medical records including test results. Any request you make is considered a Data Subject Access Request.

Most GPs practices expect you to make a request in writing at reception and then you have to wait a few days before they give you the results. You can be charged either a few pence for the print out or £10 depending on the bloody mindedness of the practice.

More info on it here:

and here:

Finally if any medical staff whether they are at your GP's practice or a hospital completely refuse to give you your records then make a Data Subject Access Request in writing sending the letter by recorded delivery. State in the letter you made a early request at reception with the date.

If they then refuse to give them to you after this letter then escalate either to your MP or the Office of the Information Commissioner. (You need the recorded delivery slip to prove you made the request.) This is because while the Data Protection Act is regulated by the Information Commissioner, a medical practitioner can be reprimanded by their professional body for not complying with the law. In the case of GPs practices it is the doctors who will be considered at fault.


I suggest you don't take any vitamin B12 supplements until you are tested for vitamin B12 and folate deficiency. This is due to the normal blood/serum vitamin B12 test being skewed if you start supplementing as you will get a reading which will just show you are taking supplements.

Once you are tested come back here and start a new thread with the test results and ranges. Posters will then advise you if you need to take any further steps.

In addition you can absorb iron well with a low B12 though you may have difficulties keeping a good level due to having heavy periods and hypothyroidism.


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