Thyroid UK
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Levothyroxine and Orlistat

Arrgghh, so frustrated, been back to my doctors after much tooing and froing. Been told my levels are no normal at 3.8. I feel more exhausted than ever and asked the doctor were there any alternatives to Levo or if there are any additional vitamins I could take to help. ... He proceeded to tell me I am exhausted because I am overweight, and not doing enough exercise. I walk 45 mins per day as I commute to work full time and I walk the dog for 30 mins each evening - which I suppose is not much...

He has prescribed Orlistat to assist weight loss as I informed him I eat healthily already. When I said I don't understand how I am so big (BMI of 35) as I was always underweight until I had thyroid issues he said "well you have never been 45 before..) He is going to see how that works out and then maybe prescribe exercise.

I know Orlistat works by expelling the fat from your body (in the most vile way possible) but if I already eat a low fat diet, I am not sure how it will work. Plus if I go back in a month and it hasn't worked I will be made to feel like a lazy failure again...

Sorry for the rant - any thoughts?

13 Replies

According to the Patient Information Leaflet, it's 3 doses a day with meals, but if you eat a meal containing no fat, you do not need to take that dose, so if you're already eating a low fat diet ...

They tried to give this to me when I put on three stone in two years, to the bafflement of everyone on the endo team at my local hospital. I turned out not to be on nearly enough medication.

Can you change your doctor?

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If the figure of 3.8 is your TSH result, you are undermedicated and will never manage to lose any weight. What is your dose currently? Best thing to do is to ask your GP for a full thyroid blood test, showing free T3 and free T4, along with the usual TSH. This will show exactly what is happening and may show a low T3 result, which is the active hormone used by your body. You should also ask him to check iron, ferritin, B12, folate and Vit D. These are often low in hypo patients and need to be high in range. When you have all your results, post them here with reference ranges of more advice.


I trust your doctor is acquainted with literature such as this (specifically the underlined bit):

Drug Saf. 2008;31(1):53-65.

Orlistat-associated adverse effects and drug interactions: a critical review.

Filippatos TD1, Derdemezis CS, Gazi IF, Nakou ES, Mikhailidis DP, Elisaf MS.

Author information


Orlistat, an anti-obesity drug, is a potent and specific inhibitor of intestinal lipases. In light of the recent US FDA approval of the over-the-counter sale of orlistat (60 mg three times daily), clinicians need to be aware that its use may be associated with less well known, but sometimes clinically relevant, adverse effects. More specifically, the use of orlistat has been associated with several mild-to-moderate gastrointestinal adverse effects, such as oily stools, diarrhoea, abdominal pain and faecal spotting. A few cases of serious hepatic adverse effects (cholelithiasis, cholostatic hepatitis and subacute liver failure) have been reported. However, the effects of orlistat on non-alcoholic fatty liver disease are beneficial. Orlistat-induced weight loss seems to have beneficial effects on blood pressure. No effect has been observed on calcium, phosphorus, magnesium, iron, copper or zinc balance or on bone biomarkers. Interestingly, the use of orlistat has been associated with rare cases of acute kidney injury, possibly due to the increased fat malabsorption resulting from the inhibition of pancreatic and gastric lipase by orlistat, leading to the formation of soaps with calcium and resulting in increased free oxalate absorption and enteric hyperoxaluria. Orlistat has a beneficial effect on carbohydrate metabolism. No significant effect on cancer risk has been reported with orlistat. Orlistat interferes with the absorption of many drugs (such as warfarin, amiodarone, ciclosporin and thyroxine as well as fat-soluble vitamins), affecting their bioavailability and effectiveness. This review considers orlistat-related adverse effects and drug interactions. The clinical relevance and pathogenesis of these effects is also discussed.

PMID: 18095746 [PubMed - indexed for MEDLINE]


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My patient leaflet for Actavis Levothyroxine has Orlistat listed as one of the medicines to tell your doctor you are taking if you are prescribed Levothyroxine!!

I'm pretty certain I've read that it can interfere with the uptake of your Levo so that's not going to help.Also it will only stop you absorbing the fat you are eating ,so if you are on a low fat diet it isn't going to do much.

I was prescribed it some years ago and have to say I lost weight,however,not long after I stopped taking it I suffered a bad gallstone attack,so just a word of warning.


Thanks all! I feel like I am going insane.... I asked the Receptionist for a print out but... "we cant do that..." Think I do need to look at changing my doctor, I felt like my weight was all my fault when I came away.

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Its vital you post your actual results and reference ranges because 3.8 means zilch

i suspect your gp has no proper understanding of thyroid and how it should be correctly tested

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I will call in again tomorrow and insist on a print out of my levels. I am on 100mg of Levo per day which my /doctor says is "working well for me" Pffftt it is not!!


I was prescribed Orlistat a few years ago and within 2 days I was folded in half with extreme stomach cramps. My GP told me to stop taking it immediately. Just recently my new GP has asked if I wanted to try it again? No thank you I have enough to put up with Fibro, RD and Osteo and possibly hypothyroid with the symptoms I have. Too much attention is being paid to the BMI as it can be incorrect if you are of short stature or muscular. Not enough attention to symptoms of hypo. Gentle hugs Joolz.x


More and more we are reading that we do need fats in our diet - of course the right ones ! Not fats included in processed foods. Have you thought of looking at The 2 Day diet by Dr Michelle Harvie and Prof Tony Howell. The two restricted days are around 1000 calories unlike some 5:2 diets that are just 500 - yikes ! On the two restricted days you are allowed 5 units of fat - one unit being a dessertspoonful of olive oil..... The other 5 days you can eat 'reasonably ' normal :-) Absolutely no carbs or sugar on the two restricted days. Of course we need carbs for balancing everything so they are eaten on the remaining 5 days...

Since menopause I have struggled with my weight but have found the results of the above pleasing...early days and yes we have lots of treats ahead which will need some discipline.

Have you had Ferritin - Folate - Iron - B12 - VitD tested ? they all need to be OPTIMAL for you to feel good and for the T4 to convert into the ACTIVE T3. T4 is just a storage hormone...and should convert when needed. Have you ever had thyroid anti-bodies tested ?

I once read that if your Doc blames your age on anything - then it is time to change your Doc.... :-)

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Called surgery today they can only give me print outs of my most recent test and for a £10 charge. Receptionist confirmed that my last test only tested the tsh levels which were 3.89 they didn't test t3 or t4 as it was a " review of medication" and that they only test fully if I am symptomatic! What was I then? Cured? This whole thing is exhausting. Trying to get appointments around working full time and then being fobbed off constantly. Finding it hard to cope.


My understanding of Orlistat is that it just makes a large amount of the fat you eat pass straight through undigested. This is why it can cause dramatic and very embarrassing side-effects!

TSH of 3.89 sounds like there is some room for increasing your dose slightly or at very least getting a T4 & T3 check to see how much actual hormones you have floating about.

If you are under medicated it will be an uphill battle to lose weight because your metabolism will be slowed down so much you will have to severely restrict calories to see any benefits.

You say you are doing a total of 1hr 15min walking per day which is quite a bit, so combined with a sensible diet you should be losing weight.


Oh and my experience is that total calories eaten is more important than dietary fat. I find a smaller serving of a full fat product is often more satisfying than a large serving of a low fat version and the total calories can be similar. What is worse is many low fat products have loads of sugar added to mask the flavour of the missing fat.

I think managing portion size is far more important than just dodging fat.


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