Is Fluoride Making You Tired? The Thyroid Link Every Midlife Woman Should Know

I was chatting with some fabulous women in one of my programs recently, and they were shocked to learn that something as simple as their toothpaste might be silently sabotaging their sleep and energy.

And, they’re not the only ones, as a YouGov sleep study found that 76% of British women say they “always” or “often” wake up tired, even when after a full night’s sleep.

Most of them had no idea why this was happening. Some thought it might be due to aging, or stress, but what if there was another factor they hadn’t considered that could be contributing to their poor quality sleep? Something like… fluoride?

Let’s dive in.

What is fluoride, and where does it come from?

Fluoride is a mineral found naturally in rocks, soil, and water. It is also added to many toothpastes because it lowers (or may lower) tooth decay in some communities.

In the UK, your exposure usually comes from a few places:

Toothpaste and mouthwash (for many adults, this is the biggest source, especially if you swallow any)
Drinking water (only some areas have water fluoridation schemes)
Tea (tea plants can absorb fluoride from soil, so strong tea can add more)
Some foods and drinks made with fluoridated water (varies by location)

Fluoride and Your Thyroid (aka Your Body’s Energy Regulator)

Your thyroid gland is one of the biggest players when it comes to energy, metabolism, mood, and brain function. To do its job, it needs iodine, an important nutrient needed for the production of thyroid hormones.

But…

Fluoride competes with iodine.

They’re both halogens, and fluoride often “wins when they’re both competing for who gets to the cell first.” That means if your body is already a bit low in iodine (which is common for a lot of women), and you’re regularly exposed to fluoride through toothpaste or tap water, or other sources mentioned above, your thyroid can’t get what it needs (iodine) to keep your energy stable.

The result?

You wake up exhausted, even after a long sleep
You feel cold, foggy, and sluggish
You can’t lose weight no matter how “healthy” you eat
You need caffeine and sugar just to function
Your digestion slows (constipation is common)

Still with me? There’s more…

Why Your Thyroid Is at the Heart of Your Energy

Your thyroid helps set your metabolic pace. It influences:

Resting energy use
Body temperature
Heart rate
Skin and hair turnover
Gut movement
Cholesterol handling
Wound healing
Mood, focus, and sleep

So when people have low energy or feel “slow,” they should be looking for anything that could block thyroid hormones.

Fluoride gets attention for two main reasons:

It is in the same chemical family as iodine (halogens). Iodine is needed to make thyroid hormone.
Historically, high doses of fluoride were once used as a treatment to suppress thyroid function in some people with overactive thyroid. I do have to point out that this is very different from modern water fluoridation levels, but if your thyroid is already underactive, or even just underperforming slightly, you can imagine why regular fluoride exposure might be a problem.

That second point is important, but do note that a lot of those were much higher amounts than what most people get from UK drinking water, but I’d still caution people with suspected or diagnosed underactive thyroid to be cautious about their fluoride intake from whatever sources they get it from.

Meet Bromine, The Hidden Ingredient That Can Also Drain Your Energy

Let’s add another piece to the fatigue puzzle: bromine.

Like fluoride, bromine is another halogen that blocks iodine from getting where it needs to go. When you’ve got too much bromine in your system, your thyroid gets even more sluggish.

And just like fluoride, bromine exposure is incredibly common, without you realising it.

Where Bromine Is Hiding

Even though some sources have been banned in the UK, bromine can still sneak into your life through:

Commercial baked goods (made with brominated flour, especially imported)
Certain fizzy drinks or sports drinks (containing brominated vegetable oil or “BVO”)
Older furniture, mattresses, or clothes (from brominated flame retardants)
Pesticide residues on non-organic produce or imported goods

While the UK banned brominated flour in 1990, brominated vegetable oil in 1970, and flame retardants in 2019, many women still have exposure through older items or non-UK imports.

If your thyroid’s already underperforming, or you’re experiencing constant tiredness, you may need to check for bromine, as it could be adding to your exhaustion load.

How It All Adds Up

These exposures might seem small on their own.

But over time, fluoride in your toothpaste + fluoride in your tap water + traces of bromine in your food or environment = tipping your energy system into a traffic jam situation.

And for a tired woman trying everything she can to have more energy and feel better?
That tipping point matters.

A tired woman trying everything she can to have more energy? That tipping point matters.

How Does Fluoride Affect You?

Energy is complex. “Low energy” often comes from a mix of:

Thyroid hormone levels and thyroid conversion (T4 to T3)
Iron status (ferritin), B12, folate
Sleep and stress load
Perimenopause and menopause changes
Blood sugar swings
Under eating, over training, or both
Inflammation, chronic pain, and gut issues

Where does fluoride fit?

Possible pathways

Here are the main proposed links:

Thyroid hormone changes: If fluoride reduces thyroid output in some people, energy production may suffer.
Iodine related effects: If iodine intake is low, the thyroid may be more sensitive to “competition” from other halogens like fluoride and bromine.
Mitochondria (cell energy): Some lab studies suggest fluoride can affect enzymes involved in energy production at higher concentrations.

Is This Relevant If You Don’t Have Diagnosed Thyroid Disease?

This means…

At high fluoride exposure, some research links it with changes in thyroid markers and symptoms.
At typical community water fluoridation levels, evidence for a meaningful effect on energy in healthy adults (but not children) is not strong, but this isn’t the only source of fluoride for most people
For someone already dealing with underactive or hypothyroid symptoms, it is reasonable to ask whether total fluoride intake is high for them personally (especially from toothpaste swallowing or high tea intake).

Fluoride, metabolism, and weight: what is realistic to expect?

People with low thyroid function often struggle with:

Low energy
Weight gain or harder fat loss
Higher cholesterol
Fluid retention
Constipation

Could fluoride meaningfully slow metabolism?

The clearest metabolism link would be through thyroid hormones, not through a direct “fat storage switch.”

A practical way to think about it:

If fluoride meaningfully lowers thyroid hormone action in your body, then metabolism may slow.
If it does not, it is unlikely to be the main driver of your weight and energy symptoms.

So the question becomes: Does your level of fluoride exposure affect your thyroid hormones?

Fluoride and thyroid hormones (TSH, T4, T3)

What happens at high exposure

In areas with high fluoride in drinking water, some studies report:

Higher TSH (thyroid stimulating hormone)
Lower T3 and T4 in some groups
More hypothyroid like symptoms

These findings are not always consistent. Many studies also struggle with confounders like iodine intake, selenium status, overall nutrition, and other water contaminants.

What about low exposure like UK water schemes?

At lower fluoride levels (around 1 mg/L in fluoridated water areas), evidence of major thyroid disruption at a population level is mixed and often weak.

That said, women 40 to 60 are not “average” in a key way: this age range includes perimenopause and menopause, when thyroid symptoms are common and autoimmune thyroid disease (like Hashimoto’s) is also common. Many women are also borderline low in iron or iodine, which can worsen symptoms.

So even if fluoride does not cause thyroid problems for most people, a smaller subgroup might be more sensitive, especially if iodine is low or thyroid autoimmunity is active.

Is Low Iodine Making You More Vulnerable?

Fluoride and iodine

Iodine is required to make thyroid hormone. If iodine intake is too low, thyroid output can drop.

In the UK, iodine intake can be low in people who:

Avoid dairy and fish
Use non-iodised salt
Eat little seafood and seaweed
Are vegan without a plan

Fluoride competes with iodine. And your thyroid needs iodine to keep your energy stable.

If you suspect that you may have low iodine, do not start using high doses of iodine to counteract fluoride or bromine on your own. High doses can worsen thyroid autoimmunity in some people. You may wish to discuss testing and/or food based improvements with your GP or a health practitioner.

Fluoride and sex hormones (oestrogen, progesterone, testosterone)

This is the area with the most confusion online.

Here’s what you need to know:

Menopause symptoms are strongly driven by changing oestrogen and progesterone, triggering as well as worsening sleep disruption, and your stress response.
Thyroid symptoms overlap heavily with perimenopause symptoms (fatigue, brain fog, weight changes, mood swings, irregular cycles, dry skin, sleep issues).
The research linking typical fluoride exposure to large changes in adult female sex hormones is limited and currently, not clear.

If you have hormone symptoms, fluoride is rarely the first place to look, but its impact shouldn’t be ignored. These are, however, usually higher impact places to start:

Thyroid labs and antibodies
Iron and B12 status
Sleep and alcohol (plus other lifestyle habits)
Nutrient density
Protein intake and strength training
Perimenopause/menopause/post-menopause care and, only if appropriate, HRT discussion

What About Stress? Can Fluoride Raise Cortisol?

Fluoride and cortisol (stress hormone)

Cortisol is your main stress hormone. It follows a daily circadian rhythm and strongly affects:

Energy in the morning
Blood sugar stability
Belly fat storage patterns
Sleep quality

You may have seen claims that fluoride “raises cortisol.” In humans at normal exposure, the evidence is not strong enough to treat fluoride as a main cortisol driver.

But there is an indirect angle that you should be aware of:

If you are worried about fluoride, and you feel unsafe about your water, that anxiety can raise stress load.
If you feel unwell and keep changing supplements and filters without a plan, stress can rise further.

So if you decide to reduce fluoride, try to sort it out in a as calm, and practical way as you can. Avoid turning it into another source of daily stress that can worsen your stress hormones balance.

Fluoride and insulin (blood sugar hormones)

Insulin controls how you store and use glucose. Perimenopause can make blood sugar swings more common, especially with poor sleep.

Chronic fluoride exposure may act as a mild endocrine disruptor in some people, potentially worsening insulin resistance and thyroid function, which together can affect blood sugar control and contribute to fatigue. The evidence in humans at typical drinking‑water levels is mixed and not definitive, but several pathways are biologically plausible.

Insulin and thyroid hormones closely influence each other because thyroid problems can worsen insulin resistance (when your body stops responding to insulin), and insulin resistance can also affect thyroid function, because both pathways are linked to fatigue and low energy.

Some studies have explored fluoride and glucose metabolism, and found that although fluoride can affect blood sugar and thyroid as mentioned above, the bigger blood sugar levers are:

Sleep length and consistency
Protein and fibre at breakfast
Strength training
Alcohol intake
Stress management
Treating thyroid dysfunction if present

However, if you suspect blood sugar issues, ask your GP about HbA1c and fasting glucose, and track how you feel after meals for a couple of weeks, but also be aware of the potential impact of fluoride which may worsen the load or impact of the blood sugar levers.

Thyroid Symptom Basics

If you do have underactive thyroid symptoms, while fluoride is not a substitute for proper thyroid evaluation, do keep in mind the impact it can have on nutrients your thyroid uses. Also consider private testing or ask your GP about:

TSH
Free T4
Free T3 (not always offered, but worth discussing)
Thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) if autoimmune thyroid disease is suspected
Ferritin, B12, folate, vitamin D
Iron panel (serum iron, ferritin, TIBC, transferrin saturation %)
Lipids (cholesterol can rise when thyroid is low)

Track symptoms for 2 to 3 weeks:

Morning energy (1 to 10)
Afternoon energy dips (yes or no)
Constipation (yes or no)
Cold intolerance (yes or no)
Sleep quality (1 to 10)

This makes it easier to see patterns and helps your clinician know what, and how best to adjust your care.

And if you’re still wondering whether your thyroid might be playing a bigger role in your low energy, brain fog, or stubborn weight issues…

Take the free Thyroid Quiz here and get your personalised score in under 2 minutes.

How to lower fluoride exposure safely

You don’t need to throw everything out, or obsess over every label.

Instead, I recommend focusing on what you do every single day, such as:

Switch to a Fluoride-Free Toothpaste

If fluoride competes with iodine, and you’re using it twice a day, it’s another easy place to make a change. You’ll still be protecting your teeth (I promise), but with formulas that don’t put your thyroid at risk.

For many women, especially if you have a high caries rate, gum recession or dry mouth in menopause, you may have been told that fluoride toothpaste helps prevent caries/cavities. If you stop fluoride, you do need an alternative to protect your teeth.

I like, and use in rotation, fluoride-free toothpastes like Boka, Risewell, Gutology, (see more on these below), but you may also wish to talk to your biological dentist about other options.

Filter Your Tap Water

Check if your water supplier adds fluoride or if your area has higher natural fluoride.

If you want to reduce fluoride in water, note that common jug filters may not remove much fluoride.

Installing a water filter (ideally one that targets fluoride) means you’re no longer drinking something that could suppress your energy systems.

I prefer and use the Berkey water filters with additional arsenic and fluoride filters (this is an affiliate link, which means I may earn a small commission if you choose to buy, at no extra cost to you).

Add Iodine-Rich Foods

Be careful about supplementing blindly with iodine, especially if you have Hashimoto’s or suspect you may have it.

Instead look into adding in natural, food-based sources of iodine to support your thyroid if you’ve been shown to be low in iodine.

If you’re already low in iodine or dealing with thyroid symptoms, even small fluoride exposures can add up.

Try including:

Seaweed (like nori, dulse, or wakame, sprinkled on rice or in miso soup)
Wild-caught fish (like cod, haddock, sardines)
Pasture-raised eggs (bonus: also support B12 and selenium levels)

Note: If you’ve already been diagnosed with Hashimoto’s or are working with a practitioner, check whether iodine is appropriate for you. It’s powerful, but isn’t for everyone.

Stop swallowing fluoride toothpaste

Use a pea sized amount, and spit out once you’re done. This is especially important for those using fluoride toothpastes. I personally don’t use fluoride toothpastes, but I also prefer to avoid rinsing right after brushing, as I prefer to have the nano-hydroxyapatite coating my teeth do double duty.

Check your tea habit

If you drink a lot of strong tea daily, consider reducing total cups you have daily, as well as trialling using shorter brew times. You may also want to rotate with lower fluoride options like herbal teas, and choose organic options as they may have less fluoride.

Avoid Bromine Where Possible

Here’s where to make easy swaps that lower your bromine exposure over time:

Check baked goods → Buy from UK brands (bromated flour is banned here) or try making your own.
Skip fizzy drinks with BVO → Look for “brominated vegetable oil” on the label and leave it on the shelf.
Review old furniture or mattresses → If you’ve had yours for over a decade, this might be worth flagging for future upgrades.

These swaps may not seem like they’ll have much impact, but over time, they lighten the load on your thyroid, reduce interference, and help your body respond better to the rest it’s already trying to get. You don’t have to do them all at once, that’s a recipe for adding more stress to your life, but choose one you feel fits in best with your life or energy levels for now, and see how you feel. Add others as you go on, or as needed.

My Top Picks for Fluoride-Free (and Gluten-Free) Toothpastes That Work

If you’re ready to switch but don’t want to waste money trying 10 brands that don’t work, here are the ones I personally recommend (and why):

Boka + Wellnesse Toothpastes (My personal favourite)

Both use nano-hydroxyapatite for remineralisation
Ideal if you want a sleek, modern brand with solid science behind it
Fluoride-free, non-toxic, and gentle on enamel

RiseWell Toothpaste

Uses hydroxyapatite, a natural mineral that rebuilds tooth enamel
Tastes great, works brilliantly, and supports your long-term oral health
Free from fluoride, SLS, artificial sweeteners, and gluten

Think: science-backed, dentist-developed, and totally thyroid-friendly.

Auromère Herbal Toothpaste

Ayurvedic blend of clay and plant extracts
Zero fluoride, no artificial nasties
A good option if you prefer something earthy and holistic

Dr. Bronner’s All-One Toothpaste

Made with organic coconut oil, aloe, and baking soda
No fluoride, no artificial flavours, and available in fun flavours like peppermint or cinnamon
Great for families or anyone just starting the fluoride-free journey

Gutology Toothpaste

Developed by gut health experts, designed with microbiome-safe ingredients
Fluoride-free, gentle on sensitive systems, and free from harsh foaming agents
A great choice if you want to support oral and gut health in one step

Let’s recap for a second

If you’ve been waking up tired, even after 8+ hours of sleep…
It may be because your thyroid may be under more pressure than you realise.

And everyday things like fluoride and bromine may be part of the reason.

Fluoride can affect the thyroid in susceptible women.
At typical UK fluoridation levels, strong thyroid effects are not clearly proven at a population level, but cumulative effects especially with other sources of fluoride need to be taken into account.
If you already have thyroid symptoms, your personal total fluoride intake is even more important.
Educate yourself on other big drivers of low thyroid symptoms in midlife: proper thyroid testing, iron and B12 status, sleep, stress, and menopause support.
Switch your toothpaste
Filtering your water
Be mindful of what’s in your home
Supporting your thyroid through food

Still Tired, Even After a Full Night’s Sleep?

If your thyroid is underperforming due to pressures from hidden sources like fluoride or bromine, no amount of “early nights” will fix the fatigue.

Take my free Thyroid Quiz to find out in under 2 minutes if your symptoms are due to a slow thyroid.

It’s gives you:

A personalised score based on your symptoms
Insight into whether your thyroid might be struggling more than you realise
Clear next steps you can take to start feeling like yourself again

👉 Click here to take the 2-minute quiz now

Still Tired, Even After a Full Night’s Sleep?

I’d love to know, did any of this surprise you?

Already switched to fluoride-free toothpaste? Or wondering which one to try first? Drop a comment and let me know. I’ve tried them all and I’m happy to help.

References

Peckham, S., Lowery, D. and Spencer, S. (2015) ‘Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water’, Journal of Epidemiology & Community Health, 69(7), pp. 619–624.
Available at: https://jech.bmj.com/content/69/7/619 (Accessed: 4 February 2025).

Ferreira, M.K.M., et al. (2024) Is there any association between fluoride exposure and thyroid function modulation? A systematic review. International Journal of Environmental Research and Public Health, [online] 21, 38593166. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11003687 (Accessed: 4 February 2025).

Barberio, A.M., Hoseini-Nasab, Y., Mahvi, A.H. and Yousefi, M. (2017) ‘Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation’, Journal of Epidemiology & Community Health, 71(10), pp. 1019–1024.
Available at: https://jech.bmj.com/content/71/10/1019 (Accessed: 4 February 2025).

American Thyroid Association (ATA) (2015) Is fluoridated drinking water associated with a higher prevalence of hypothyroidism?, 8(6).
Available at: https://www.thyroid.org/patient-thyroid-information/ct-for-patients/volume-8-issue-6/vol-8-issue-6-p-3(Accessed: 4 February 2025).

Griebel-Thompson, A.K., Egan, K., O’Leary, M. and Zimmermann, M.B. (2023) ‘A Scoping Review of Iodine and Fluoride in Pregnancy in Relation to Maternal Thyroid Function and Offspring Neurodevelopment’, Advances in Nutrition, 14(2), pp. 317-338.
Available at: https://doi.org/10.1016/j.advnut.2023.01.003 (Accessed: 4 February 2025).

Boas, M., Feldt-Rasmussen, U. and Main, K.M. (2012) ‘Thyroid effects of endocrine-disrupting chemicals’, Molecular and Cellular Endocrinology, 355(2), pp. 240–248.
Available at: https://doi.org/10.1016/j.mce.2011.09.005 (Accessed: 4 February 2025).

Zhou, T., Ross, D.G., DeVito, M.J. and Crofton, K.M. (2001) ‘Effects of short-term in vivo exposure to polybrominated diphenyl ethers on thyroid hormones and hepatic enzyme activities in weanling rats’, Toxicological Sciences, 61(1), pp. 76–82. Available at: https://doi.org/10.1093/toxsci/61.1.76 (Accessed: 4 February 2025).

National Library of Medicine, 2004. Metabolism of bromide and its interference with the metabolism of iodine, [online] Available at: https://pubmed.ncbi.nlm.nih.gov/15119938 [Accessed 4 February 2025].

U.S. Food and Drug Administration (FDA) (2023) FDA revokes regulation allowing use of brominated vegetable oil in food.
Available at: https://www.fda.gov/food/hfp-constituent-updates/fda-revokes-regulation-allowing-use-brominated-vegetable-oil-bvo-food (Accessed: 4 February 2025).

Bianco, A.C. and Kim, B.W. (2006) ‘Deiodinases: Implications of the local control of thyroid hormone action’, Journal of Clinical Investigation, 116(10), pp. 2571–2579.
Available at: https://doi.org/10.1172/JCI29812 (Accessed: 4 February 2025).

Mullur, R., Liu, Y.Y. and Brent, G.A. (2014) ‘Thyroid hormone regulation of metabolism’, Physiological Reviews, 94(2), pp. 355–382.
Available at: https://doi.org/10.1152/physrev.00030.2013 (Accessed: 4 February 2025).

Schlagenhauf, U., Kunzelmann, K.H., Hannig, C., May, T.W., Hösl, H. and Probstmeier, R. (2021) ‘Impact of a toothpaste with microcrystalline hydroxyapatite on the prevention of caries: A randomized clinical trial’, Scientific Reports, 11(1), 23517.
Available at: https://www.nature.com/articles/s41598-021-81112-y (Accessed: 4 February 2025).

YouGov (2023) Sleep Study.
Available at: https://yougov.co.uk/health/articles/42957-yougov-sleep-study (Accessed: 4 February 2025).