I have just read that Syndol (an over the counter painkiller) should be used with caution in hypo people. Does anyone know why that might be? The ingredients are: paracetamol, codeine phosphate, doxylamine succinate and caffeine.

Unfortunately, the original Syndol have been available for ages due to a licensing issue and I am considering paying £££££s to buy some online...but may think again depending on why I would need to use caution. Any ideas anyone? Cheers.

27 Replies

  • I think it's one of the ingredients which is the problem.

  • Syndol is no longer available over the counter in UK chemists. Don't know why it has been taken off the market. I have used Syndol but only in relation to stress related headaches. Would never have associated it with any thyroid problems.

  • The latest UK information says they do NOT contain doxylamine succinate (although old formulations did).

    They seem to be co-codamol with caffeine.


  • Yes I know Rod :-( Without the doxylamine they are just the same as any common or garden painkiller which is why I was considering buying some from overseas.

    I haven't noticed that they have any effect on my Levo either Shaws, so I might take the plunge. I don't take them very often so I should be OK I think.

  • Looks like it has a pretty significant effect on T4 levels - and, I assume consequently, on TSH.

    Toxicol Appl Pharmacol. 1996 Dec;141(2):584-94.

    Effects of doxylamine succinate on thyroid hormone balance and enzyme induction in mice.

    Bookstaff RC1, Murphy VA, Skare JA, Minnema D, Sanzgiri U, Parkinson A.

    Author information


    The effects of doxylamine (as the succinate salt) on microsomal enzyme activity and serum thyroid hormone levels were examined in B6C3F1 mice following dietary exposure for 7 or 15 days (0, 40, 375, 750, or 1500 ppm in diet, expressed as free base doxylamine). In addition, the hepatic P450 enzyme inducer sodium phenobarbital (375 ppm, expressed as free acid phenobarbital) was used as a positive control for CYP2B induction. Exposure of mice to doxylamine produced dose-related increases in liver weight at both time points. Liver weights were also increased in the phenobarbital-treated mice. Doxylamine treatment caused a dose-dependent increase (up to 2.6-fold) in liver microsomal cytochrome P450 in both male and female mice, at both time points. Analyses of the activities of various hepatic microsomal cytochromes P450 indicated that doxylamine caused a marked induction of CYP2B enzymes. This was demonstrated by a large increase in the O-dealkylation of 7-pentoxyresorufin (up to 38-fold) and the 16beta-hydroxylation of testosterone (up to 6.9-fold), both of which are indicative of CYP2B induction. In addition, like phenobarbital, doxylamine treatment resulted in a modest induction of CYP3A and CYP2A enzymes and approximately a 50% increase in thyroxine-glucuronosyltransferase activity. Doxylamine did not appear to induce P450 enzymes in the CYP1A, CYP2E, or CYP4A enzyme subfamilies. None of the enzyme-inducing effects of doxylamine could be distinguished from those of phenobarbital. These results suggest that doxylamine is a phenobarbital-type inducer of liver microsomal cytochrome P450 in B6C3F1 mice. Exposure to either doxylamine or phenobarbital also resulted in decreases in serum thyroxine (T4) levels (approximately 80% of control) with compensatory increases in serum thyroid-stimulating hormone levels (approximately 4-fold). No clear changes in serum triiodothyronine levels were apparent. These findings are consistent with the hypothesis that doxylamine increases the activity of those hepatic enzymes involved in T4 metabolism.




  • Bad news :-( Syndol has been my drug of choice for ages now, though I have always been super careful never to take too many in case my body got used to them.

    Funnily enough, I noticed a couple of days ago that my temperature had gone down by a little bit and I couldn't work out why so now I'm wondering if the one tablet I took was responsible. Seems pretty likely given that information?

    They are SO fantastic and the only thing that sorts out my pain so this is a real blow to me. I'm glad I have been so careful with them! I have two left in my stash so might keep them for when I'm really desperate then after that...back to the drawing board I guess.

    Thanks very much for your help x

  • I take Cocodamol with 1/4 of a Sleep Aid tablet by Kirkland (100% Doxy) just like having the original Syndol. You can buy Sleep Aid on, real cheap too.

  • Hi Darren, apparently the Doxy (which is the magic ingredient in the original Syndol) is a no-no for hypo people. Syndol actually says in the accompanying leaflet that it's to be taken with caution if you have thyroid problems

  • I do exactly the same. 1/4 of a Kirkland tablet and cheap packet of cocodamol from chemist. It does the same job as Syndol at a fraction of the price.

    I also find that when I have a less painfull headache or Migraine I may not even need the cocodomal.

  • Oh dear not good news! I buy online and do use it intermittently for my chronic headache.

  • May be because of the caffeine? I have removed as much caffeine as I can from my diet since having RAI.

  • May be because of the caffeine? I have removed as much caffeine as I can from my diet since having RAI.

  • Hi, I am hypo and I took Syndol for 15 years without any problem. I have migraines not too often now, but when I get them I cannot function. Also, I had a hysterectomy for endometriosis and fibroids and took syndol for the pain. Prescription medication like solpadol didn't agree with me, and I cant take cocodomol due to bowel problems. Kapake made me feel like I was drugged - didn't like that.

    Yes, there has been the licensing problem with it, and one chemist would not sell me 2 boxes in one transaction. I then called my sister who I lived near at the time and she went in and got them for me. We don't speak now so it would not be an option now, and I live 50 miles from her now.

    Not seen Syndol for a while, however, from what I gather they have changed the recipe and taken out the doxylamine succinate which was the best ingredient, so I wont be buying it in the UK. Also, I wont pay ridiculous prices for it from Africa which is 3 x the UK cost! I am living on 72.50 per week and that doesn't cover my food bill alone, so am using credit card for petrol to get to the nearest town 8 miles to get food ect grr

    Syndol worked well for me when it was available, though have been without it for around 2 years and when I get migraines now, I cant leave a dark room and have a bucket for the sickness.x

  • Glynisrose, no it seems it's the Doxylamine that's the problem. The new version still contains caffeine but doesn't have the warning for hypos.

    Pinkgirl, I was on the brink of ordering some from S Africa! They are very expensive but per tablet I reckoned it would be worth it. My neck is going daft this morning and there are two winking at me in my bedside drawer but I have resisted so far. They did not appear to affect me adversely but my temperature is still down so they must be doing something :-(

  • I always used one Syndol and one paracetamol on the rare occasions that I did my back in if I bend suddenly.

    I have done that stupid trick ever since it first happened in the 80's while I was hanging long curtains in a precarious manner!

    I pull the muscle in my lower back near my hip. It's agony and takes over a week to get better. it makes it very difficult to move, stand up, straighten up, sit down, in fact you name it you can't do it!

    Syndol used to relax the muscle and help sort it out.

    In the early 70's I injured my neck and the doctor gave me a private prescription for Syndol after he wouldn't give me a third week of a tranquiliser in case of dependency.

    Over the years Syndol became my go-to for my back and muscle strain whenever it happened, which thankfully didn't very often, sometimes I'd go for a year or more without.

    9 days ago it happened again so I started researching Syndol suppliers as I had long ago finished those I had in the medicine cupboard.

    After finding them on sale once more but lacking the important ingredient, I started the search for that ingredient and found it sold as a sleeping aid, so I ordered some a few days ago.

    They haven't arrived yet but thankfully since yesterday I am able to move with barely any pain, just a twinge or two.

    Anyhow to get back to the point, the Doxylamine tablets sold contain 25mgs of the ingredient each. Syndol contained 5mgs if I remember correctly.

    I do have a pill cutter, a few years ago one of my cats had to have a pill chopped up that was too tiny to divide any other way.

    What I thought I would do the next time I need it, is to cut one tablet up into quarters and take a quarter along with a paracetamol.

    I doubt if that would do me much harm but it would take the edge off any pain and help the muscle to recover.

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  • Hi Ellie-Louise, I have read about the Sleep Aid tablets before and have been tempted, but now I am a bit concerned about the affect they will have on my thyroxine. I wouldn't have thought one little tablet would do much harm but my (already low) temperature has gone down and I can't see any other reason for it. I am absolutely gutted....I loved my Syndol!! I used to pop one at night, sink into a lovely sleep and wake up pain free. Will you let me know how you get on with the Sleep Aid?

  • Will do.

    I'm on 50mgs Levothyroxine which I take at night, actually I should say early hours. lol

    I play GTA5 online after my husband goes to's my 'me' time...and all my friends are American. :)

    I've been hooked on that game forever.

  • Snap - I take mine in the early hours too...not because I'm gaming but because I'm always weeing!

  • Not that pleased with Biovea's service!

    I ordered on January 10th. This morning they sent me an email stating my order would be despatched today (January 16th.)

    If you take out two days for the week-end it still leaves four days when nothing appeared to be happening.

    Most companies you order from will post out the next day. I wonder how long it'll be now it's in the postal service.

  • I found that pain killers,specifically opiates,have an insulin resistance effect due to the mu (greek character mu) opiate receptor...I became over 99 percent insulin resistant due to pain killers acc to one lipid specialist probly caused my high I live in pain and have high lipids,fat,and insulin resistance

  • If that's not enough to put anyone off I don't know what is. You poor thing. Did you take a lot of painkillers?

  • I took them as prescribed against my best instincts round the clock...rheumatologist insisted fibro was getting worse when actly the parathyroid adenoma, causing hypercalcemia and bone joint pain,is what was getting worse. None of my doctors put the low D, high Ca,muscle spasms,tachycardia,bone pain chiropractor sussed it up on the first visit when he saw a calcified thyroid on the neck xray,and my pharmacists warned me my doc had me on too much pain meds for someone wt cancer or MS.

    I figured it out by demanding an endo referral...even then had to convince endo smtng new was wrong...once dx of fibro here, you r blown off by doctors

  • That's dreadful-you have really put my problems into perspective. I can only hope things turn around for you somehow. Take care x

  • Not related to Hypo but I have been told by a consultant that my daughter once saw that Syndol if taken frequently can cause cluster headaches and told her not to take it. Lots of anti inflammotory drugs can have bad side effects it seems if taken frequently.

  • Really? I heard something on the tv just last week about cluster headaches saying they were one of the most painful things we can suffer. Happily I didn't get any-but then I was very careful and didn't take them very often.

  • I take Cocodamol with 1/4 of a Sleep Aid tablet by Kirkland (100% Doxy) just like having the original Syndol. You can buy Sleep Aid on, real cheap too.

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