Caffeine and Your Thyroid

If you have thyroid issues (especially Hashimoto’s), adrenal fatigue, insomnia or trouble sleeping, anxiety etc. it’s important to be aware of the impact of coffee on your thyroid and thyroid medications. 

Increases blood sugar

According to this study, caffeine heavily increases our blood sugar levels when consumed.  Blood sugar spikes cause cortisol to shoot up, which tires out the adrenals and can exacerbate hypoglycemia, Hashimoto’s and adrenal fatigue. Not good!

I have covered in another post why so many of us with thyroid problems are likely to suffer from blood sugar imbalances, so this is a serious thing to consider and explore. If you get ‘hangry’ (hungry and angry), dizzy, faint and irritable when hungry, you could well have blood sugar imbalances.

Tires out the adrenals

As touched on above, caffeine makes our blood sugar spike, which causes the adrenals to pump out more cortisol. Also, when your blood sugar levels drop below normal, sometimes after a spike, your adrenal glands respond by secreting cortisol. This cortisol then tells the liver to produce more glucose, which brings blood sugar levels back to normal. Doing this repeatedly can cause abnormal cortisol output and can suppress pituitary function.

Drinking coffee whilst also having adrenal fatigue is only adding fuel to the fire.

Damages gut lining and encourages acid reflux

Coffee can irritate the esophagus or weaken the lower esophageal sphincter, which prevents the backward flow of stomach contents that causes reflux. Therefore, it can encourage acid reflux.

Coffee is highly acidic, so as Hypothyroid Mom explains, it stimulates the release of gastrin and bile. For people with autoimmune conditions, compromised digestion (such as IBS or leaky gut), this can cause further digestive damage to the intestinal lining.

Causes migraines

Caffeine can trigger migraines and headaches. Since caffeine narrows the blood vessels that surround your brain, when you stop consuming it, they expand again, and this can cause pain. It’s easy for your body to get used to caffeine, and when you don’t have it in your system, you can have a withdrawal headache or migraine. You may have one cup a day at work, then on the weekends don’t drink it, and experience caffeine withdrawal headaches/migraines. This is a sign of addiction and your body being used to it, if it doesn’t do well without it.

If you get migraines or headaches, you should avoid caffeine to avoid it making matters worse.

As explained above, the spike in blood sugar caused by caffeine, could also cause headaches.

Some women experience migraines around the time of their period (this was also me!), possibly because of changes in the level of oestrogen around this time, and as the below explains, caffeine affects oestrogen levels, too..

Can cause too much oestrogen

Studies have shown that women who consumed at least 500 milligrams of caffeine daily, the equivalent of four or five cups of coffee, had nearly 70% more oestrogen.. than women who consumed no more than 100 mg of caffeine daily (less than one cup of coffee). Tea is not much better as it contains about half the amount of caffeine compared to coffee.

Hypothyroid Mom says that PMT, lumpy breasts, heavy periods, cellulite and even breast cancer can be symptoms of estrogen dominance.

Oestrogen dominance inhibits T4 to T3 conversion.

Affects  the conversion of T4 to T3

It’s well reported by many thyroid sources such as Hypothyroid Mom and Mary Shomon, that coffee impacts the absorption of T4-only thyroid medication Levothyroxine, which  is why thyroid patients need to wait at least an hour after taking their Levo before drinking any tea or coffee. I personally would avoid caffeine within an hour of taking any thyroid medication, not just Levothyroxine, just to be sure.

Another option may be to take levothyroxine medication at night. Some studies have shown that taking levothyroxine at bedtime may improve absorption. It also allows for you to have your morning cup of coffee without worrying about it affecting your thyroid medication.

However, with the information shown in this article, I would still suggest staying away from coffee altogether!

Coffee contributes to oestrogen dominance, and, as explained above, estrogen dominance inhibits T4 to T3 conversion.

Contributes to insomnia and poor sleep

This study showed that 400mg of “caffeine taken 6 hours before bedtime has important disruptive [sleep] effects” though this can be dependent on the individual and their ability to metabolise caffeine. It’s well reported to avoid caffeine after lunch time.

As explained above, caffeine exhausts the adrenals, and a key sign of adrenal dysfunction includes trouble getting to sleep and/or staying asleep.


I suggest that all thyroid patients give up caffeine to see if/how it affects them. At least a week should be given without it to see changes. If you find it really difficult, then it gives an idea of how addicted you could potentially be to the substance.

People who give up caffeine tend to report better sleep, less headaches, fewer hot flashes, less anxiety, and less hypothyroid symptoms. I realised that caffeine was contributing to my migraines, so I cut it out, and haven’t looked back since.

You can click on the hyperlinks in the above post to learn more and see references to information given, but more reading and references can also be found at:

http://hypothyroidmom.com/11-ways-coffee-can-impact-your-thyroid/

https://www.drlam.com/blog/estrogen-dominance-part-1/1704/

https://www.verywell.com/secret-about-coffee-and-your-thyroid-3233287

http://www.healthline.com/health/gerd/coffee-tea#FoodandGERD1

http://www.nhs.uk/Conditions/Migraine/Pages/Causes.aspx


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-Rachel

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