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Does Sunscreen Affect Your Thyroid Gland?

Learn which ingredients in sunscreen can interfere with thyroid function, and how to choose a better option.
Does Sunscreen Affect Your Thyroid Gland?
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In this article:

  • What ingredients are in sunscreen?
  • What ingredients are “endocrine disrupters?”
  • Why are endocrine disruptors harmful to people with thyroid conditions?
  • Does sunscreen affect vitamin D absorption?
  • Tips for choosing a sunscreen if you have Hashimoto’s

Sunshine is vital for our health and wellbeing. It helps us synthesize vitamin D in our skin and boosts our mood. But, as most of us are aware, too much sunshine can increase your risk for skin cancer. People are encouraged to wear sunscreen to combat sun damage, but not all sunscreens are created equal. And, not all sunscreen ingredients are safe for everyone. Here’s what people with Hashimoto’s thyroiditis need to know about when looking for a safe, non-toxic sunscreen.

What ingredients are in sunscreen?

Most of us pay little attention to what ingredients are in our sunscreen. Often, we look for a familiar name brand or logo and grab it off the shelf. But, the skin is like a giant sponge. Whatever we put on it will readily absorb into the deeper layers of our skin and eventually our bloodstream. So, it pays to be critical of what you put on your skin.

Most sunscreens contain the following common ingredients:

  • Zinc oxide
  • Titanium dioxide
  • Oxybenzone
  • Octinoxate
  • Homosalate
  • Octisalate
  • Octocrylene
  • Avobenzone
  • Parabens and phthalates

Usually, sunscreens contain a combination of active ingredients, except sunscreens that have zinc oxide.

In total, there are about 16 active chemicals that are currently on the market in sunscreen products. Regrettably, only two of the above ingredients are considered safe and effective per the FDA: zinc oxide and titanium dioxide. Of these 16 ingredients, two are NOT safe and should NOT be included in sunscreen for safety purposes: PABA and trolamine dioxide. The remaining 12 ingredients do not have sufficient data to support their safety and efficacy.

Within the last year, some studies have shown that these ingredients can be detected in the skin and blood weeks after their last use. In addition, these ingredients may even be detectable in urine and breast milk. 

What ingredients are considered “endocrine disrupters?”

Some ingredients commonly found in sunscreens are known endocrine disrupters. Endocrine-disrupting chemicals (EDCs) are chemicals and other substances that interfere with the normal functioning of your body’s endocrine system. Endocrine glands are hormone-producing glands like the thyroid and adrenals. 

Some EDCs mimic your hormones, and others block your hormones from doing what they need to do. Then, of course, some EDCs raise or lower the hormone levels in your blood. 

There are a few known or suspected EDC’s that may be in some sunscreens:

  • Oxybenzone (or benzophenone-3) is an EDC that has been shown to lower testosterone in young men and is a contact allergen and may cause organ toxicity. 
  • Octinoxate (OMC) is another EDC that may also cause reproductive toxicity.
  • Homosalate may be toxic to reproductive organs and interfere with normal development.
  • Parabens and phthalates are well-known EDC’s. (Keep in mind, phthalates often hide under the umbrella of “fragrances” in skincare products).

Why are endocrine disruptors harmful to people with thyroid conditions?

EDC’s alter your hormones in some way. For example, they may increase or decrease hormone concentrations, mimic hormones, or block them altogether. As a result, these chemicals are problematic for anyone with hormones—which is, well, everyone. Still, it is especially concerning for people who already have trouble regulating their hormone levels. 

People with hypothyroidism are already fighting an uphill battle trying to regulate their thyroid hormones. Once you find the correct dose of thyroid medication to keep your thyroid hormones at an optimal level, you don’t necessarily want to mess with it unless another circumstance requires a dose change (like pregnancy). 

However, suppose you regularly apply a product on your skin that has EDCs. In that case, it may start to interfere with your glands and even your medication.

While you should be wary of EDCs in your sunscreen and other products you use, this is not to say you should avoid sunscreen altogether. On the contrary, we still recommend you wear sunscreen to help prevent skin cancer and block harmful UV rays. You just want to be a bit more selective with what you put in your shopping cart—especially if you have a thyroid condition.

Does sunscreen affect vitamin D absorption?

Vitamin D is necessary for healthy bones and optimal organ functioning, including the thyroid. We make vitamin D when our skin is in sunlight. We can also get it from our diet.

Some people worry that regular sunscreen use blocks your absorption of vitamin D. Indeed, it is a bit of a controversy. Many people do not use sunscreen regularly because they worry about vitamin D deficiency

Per the Skin Cancer Foundation, no studies claim that regular sunscreen use leads to vitamin D deficiency. Indeed, they argue that the risk of skin cancer is far greater than the whisper of a possibility that sunblock can lead to low vitamin D levels. Even if you use sunscreen regularly, it is unlikely you will always cover every exposed area of your skin, every moment you are in the sun. Thus, you will still absorb vitamin D from the sun in those unprotected areas. 

Chart with photos of ten safe sunscreen options for thyroid patients

Tips for choosing a sunscreen if you have a thyroid condition

Read the ingredient label

If you have Hashimoto’s, or any thyroid condition for that matter, it is crucial to study the ingredients in your sunscreen. Of course, you don’t have to memorize all of the potential ingredients in your sunscreen. Still, it can help to remember that zinc oxide and titanium dioxide are generally safe and effective sun protection for most people. 

Choose a broad-spectrum sunblock

Broad-spectrum means that it protects you from both UVA and UVB rays, which contribute to melanoma. When you are looking at SPF ratings, that only measures the levels of protection against UVB rays.

Choose a cream over a spray or powder

Creams generally protect your skin better, and there is less risk of chemical inhalation of toxic ingredients.

Choose a sunscreen between 30-50 SPF

Sunscreens higher than 50 SPF have no additional benefits.

Avoid products that also protect against bugs

Sunscreen products that also claim to be bug spray are generally not as effective as sunscreen alone. 

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Julia Walker, RN, BSN

Clinical Nurse

Julia Walker, RN, BSN, is a clinical nurse specializing in helping patients with thyroid disorders. She holds a Bachelor of Science in Nursing from Regis University in Denver and a Bachelor of Arts in the History of Medicine from the University of Colorado-Boulder. She believes managing chronic illnesses requires a balance of medical interventions and lifestyle adjustments. Her background includes caring for patients in women’s health, critical care, pediatrics, allergy, and immunology.

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