Thyroid UK
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Hypo/ hashis and doxylamine succinate aka sleep aid

Hi there, I work the night shift five nights a week every week. I find it very hard to sleep during the day so lack of sleep causes stress, cortisol and adrenal distress. I have recently started taking "sleep aid" - one 25g tablet of doxylamine succinate - I take this four mornings a week when I return from work. I have had huge success with this, and feel 100 times better. No hangover, weird dreams, anything like that, just a good 7 hours sleep. My question is this - I have recently read that this particular drug is not so good for hypo/hashis sufferers. Can anyone tell me the reason? It would have to be particularly compelling to stop me using it - lack of sleep is devastating to your quality of life - being hashis/hypo is a doddle in comparison. No danger of getting addicted, and I only work nights seven months a year. I sleep normally (ish) on my two nights a week off. Hope someone can enlighten me on this.

4 Replies

Welcome to the forum, Reliablerebel.

I Googled "Doxylamine + Hypothyroidism" and "Doxylamine + Levothyroxine" and didn't get any hits suggesting Doxylamine is contraindicated with hypothyroidism or Levothyroxine.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

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But there is this:

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.

PMID: 8975784 [PubMed - indexed for MEDLINE]

What to make of it is another matter. :-(


Yes I read this too - but was not entirely sure what it meant!! Glad I am not the only one. Thanks for your reply x


Thanks - it seems information on this is a bit scarce - which is probably a good thing. I felt if anyone on here had heard of this I would have got a few replies. I know that the doxylamine itself is not without problems, and am aware of that - but lack of sleep is also a major problem, so am willing to continue. However, if there was research to suggest it would also affect hypo/hashis I would reconsider my decision. I appreciate you taking the time to reply.


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