How to Keep Your Thyroid Safe During the Summer

In this article

Summer is officially here. The days are longer, the sun is brighter, and many of us are spending more time outside. Whether you’re diving into a swimming pool, enjoying backyard barbecues, reaching for sunscreen or bug spray, or catching a fireworks show, summer offers some of the best memories of the year.

But there’s a hidden side to the season that often goes unnoticed: the impact of common summer exposures on your thyroid. When you have Hashimoto’s thyroiditis or hypothyroidism, or you’re simply trying to protect your thyroid health, you’ll want to understand how some seemingly harmless summer activities might be introducing endocrine-disrupting chemicals or thyroid-interfering compounds into your routine.

Let’s take a closer look at five common elements of summer — swimming pools, sunscreen, bug spray, deodorant, and fireworks — and explore how they could affect your thyroid health, plus what you can do to make smarter, safer choices this season.

Cooling off in a pool is a summer staple — but it’s also a potential source of chlorine and chlorine byproducts, which can interfere with thyroid function. 

Chlorine belongs to a group of elements called halogens, which also includes iodine — the mineral your thyroid needs to produce hormones. The problem? Halogens, such as chlorine (as well as bromine and fluorine), can compete with iodine for absorption in the thyroid gland. This can interfere with your thyroid’s ability to absorb iodine, potentially leading to hypothyroidism, especially in individuals with low iodine intake. 

More than just drinking water

While you might think the only risk is swallowing pool water, research shows that skin absorption and inhalation pose far more significant risks. One study found that children swimming for just one hour absorbed 88% of chlorine-related chemicals through their skin — and only 12% from swallowing. Similarly, adults in a 15-minute chlorinated bath absorb nearly double the amount of water and chemicals compared to drinking the daily recommended intake.

Recent findings indicate that climate change and rising temperatures can amplify chemical exposures, including halogens, in recreational water sources. These exposures may alter thyroid hormone levels, especially during the summer, when TSH and free T3 levels naturally decrease.

 What can you do? 

• Rinse off before and after swimming to reduce the formation of chloramines (irritating byproducts created when chlorine mixes with sweat or products on your skin).
• Wet your skin and hair before entering the pool to reduce absorption.
• Use a swim cap and goggles for additional protection.
• Shower immediately afterward and apply a gentle, non-fragranced moisturizer to help repair the skin barrier.
• Opt for outdoor pools with good ventilation and avoid poorly ventilated indoor pools.
• Seek saltwater or UV-disinfected pools as alternatives to traditional chlorinated pools.
• Maintain adequate iodine intake to help counteract halogen competition.

Protecting your skin from the sun is crucial, but not all sunscreens are created equal — especially when it comes to thyroid safety. 

Many people aren’t aware that out of 16 common sunscreen ingredients reviewed by the FDA, only two — zinc oxide and titanium dioxide — are currently considered Generally Recognized as Safe and Effective (GRASE). The remaining 12, including oxybenzone, octinoxate, avobenzone, homosalate, and octocrylene, are still under review due to insufficient safety data.

The problem with chemical sunscreens

These chemical filters are absorbed through the skin – often at levels above FDA safety thresholds. Ingredients like oxybenzone and octinoxate have been detected in blood, breast milk, and urine weeks after application. Several sunscreen ingredients have been linked to endocrine disruption, meaning they may interfere with hormones by mimicking or blocking them.

Animal studies have shown that certain UV filters (like 4-MBC) can decrease T4 and increase TSH, potentially indicating hypothyroid effects. Human data is mixed — but enough concern exists to warrant caution, especially for vulnerable populations.

Who’s most at risk?

• Pregnant women and fetuses, due to transplacental absorption
• Babies and children, who have more permeable skin barriers
• People with thyroid autoimmunity, like Hashimoto’s, who may be more sensitive to hormonal disruptions

 What can you do? 

• Choose mineral sunscreens with zinc oxide or titanium dioxide. These form a physical barrier and are minimally absorbed.
• Avoid spray forms of sunscreen, which can be inhaled.
• Check labels for chemical filters and opt for fragrance-free, paraben-free formulas.
• Reapply sensibly, especially if you’re using a chemical formula — absorption increases with frequency and coverage.

Protecting yourself from mosquitoes and ticks is crucial to prevent diseases such as Lyme, Zika, and West Nile. But what’s in your bug spray — and how might it affect your thyroid?

EPA-approved bug sprays often contain:

• DEET: DEET (N,N-Diethyl-meta-toluamide) is a widely used synthetic insect repellent effective against mosquitoes, ticks, and other biting insects.
• Picaridin: Picaridin is a synthetic insect repellent modeled after compounds in black pepper, offering long-lasting protection with minimal odor and skin irritation.
• IR3535: IR3535 (Ethyl butylacetylaminopropionate) is a synthetic insect repellent that is structurally similar to natural amino acids and is effective and gentle on the skin.
• Oil of lemon eucalyptus: Oil of lemon eucalyptus is a naturally derived plant-based insect repellent containing PMD, known for its strong protection against mosquitoes.
• Undecanone: Undecanone is a naturally occurring compound found in wild tomatoes that acts as a bio-based insect repellent against mosquitoes and ticks.

While these active ingredients are generally considered safe when used as directed, some products may also contain phthalates, parabens, or synthetic fragrances, all of which have been linked to endocrine disruption.

What does the research say?

There is no substantial evidence linking the use of standard bug spray to thyroid dysfunction. However, larger studies of pesticide exposure (especially among agricultural workers) found that:

• Organochlorines: Associated with a 23% increased risk of hypothyroidism
• Organophosphates: 12% increased risk
• Pyrethroids: 15% increased risk

These pesticides share chemical classes with some repellent ingredients, highlighting the potential risks of repeated or high-level exposure.

 What can you do? 

• Use EPA-approved repellents sparingly, especially on small children or pregnant women.
• Apply to clothing rather than directly to skin whenever possible.
• Avoid using repellents with added fragrance or unlisted “inactive” ingredients.
• Choose natural alternatives (like essential oil-based sprays) only in low-risk areas — they may not be effective in high-risk zones.
• Wash repellent off after coming indoors to reduce residual exposure.

You likely apply deodorant daily, especially during hot summer months. However, many conventional products contain ingredients that may not be thyroid-friendly.

The key ingredients of concern include: 

• Aluminum compounds: Used in antiperspirants to block sweat glands. Aluminum has been studied for its potential neurotoxic and endocrine-disrupting effects.
• Parabens: Preservatives that can mimic estrogen and may disrupt thyroid hormone function.
• Phthalates: Often hidden under the word “fragrance,” these can interfere with hormone signaling.

Though direct links between deodorant use and thyroid disorders are limited, the cumulative burden of endocrine disruptors from personal care products is being increasingly scrutinized.

 What can you do? 

• Switch to natural deodorants that are free of aluminum, parabens, and phthalates.
• Look for “fragrance-free” labels, as “unscented” may still contain masking agents.
• Use less or apply every other day if you’re in low-activity environments.
• Consider sweat-wicking clothing or natural odor absorbers, such as baking soda or magnesium-based formulas, as an alternative.

Fireworks are a quintessential part of summer holidays, but they come with a hidden chemical — perchlorate.

Perchlorate is a chemical used in rocket fuel, explosives, and fireworks. In addition to fireworks, perchlorate has been detected in:

• Drinking water (especially near military or industrial sites)
• Leafy greens and some produce irrigated with contaminated water
• Milk and dairy products (via animal feed)

Thyroid impact

Perchlorate is a known thyroid disruptor. It inhibits the thyroid’s ability to absorb iodine, directly impacting hormone production. Even small levels of chronic exposure can lead to:

• Decreased T4 production
• Elevated TSH
• Increased risk of hypothyroidism, especially in iodine-deficient individuals

What can you do? 

• Watch fireworks from a distance, especially if you have respiratory or thyroid concerns.
• Avoid standing downwind of displays, where smoke and particulate matter are more concentrated.
• Support local regulations to reduce perchlorate pollution in public water systems.
• Ensure adequate iodine intake, especially if you live in areas where perchlorate contamination is known to occur.

Summer is about fun, freedom, and enjoying the outdoors — and that shouldn’t change. However, if you’re managing a thyroid condition or trying to minimize risk factors, it’s helpful to be aware of environmental exposures that may contribute to your body’s burden.

Here’s your summer thyroid protection checklist:

• Choose mineral sunscreens (zinc oxide, titanium dioxide) – Mineral sunscreens offer UV protection without the use of harmful chemical filters that can act as endocrine disruptors and interfere with thyroid function.
• Rinse before and after swimming in chlorinated pools – Rinsing helps reduce the absorption of chlorine and related compounds, which may affect thyroid health by interfering with iodine uptake.
• Opt for outdoor or saltwater pools when possible – Saltwater and well-ventilated outdoor pools generally have lower chlorine exposure, reducing the risk of thyroid-disrupting chemical absorption.
• Use bug repellents wisely — and wash off after use – Many insect repellents contain chemicals that may disrupt hormones, so limit use to exposed skin and wash thoroughly afterward to minimize absorption.
• Check deodorants for aluminum, parabens, and fragrance – These ingredients may act as endocrine disruptors and are best avoided to reduce cumulative chemical exposure that could impact thyroid balance.
• Watch fireworks from a safe distance and limit smoke exposure – Fireworks release perchlorates and other toxins that can disrupt thyroid function by blocking iodine absorption, so minimize inhalation when possible.
• Maintain adequate iodine and selenium intake – Both nutrients are essential for healthy thyroid hormone production and protection against oxidative damage to thyroid tissue.‍
• Stay informed about endocrine disruptors and where they appear in daily life. Common in plastics, personal care products, and food packaging, endocrine disruptors can interfere with thyroid hormones, so awareness helps reduce exposure.

Knowledge is power — and by making informed choices, you can soak up the joys of summer and protect your thyroid health.

Are you interested in learning more? Read these articles here at the Paloma blog. 

• Does Sunscreen Affect Your Thyroid Gland? –Learn which ingredients in sunscreen can interfere with thyroid function, and how to choose a better option.
• Why The Chlorine in Swimming Pools Can Affect Your Thyroid – Before you jump into the pool, learn how chlorinated water can affect your thyroid function.
• Does Bug Spray Affect Your Thyroid Gland? – Learn what to look for and what to avoid in your bug spray if you have a thyroid condition.
• 4 Ways Conventional Deodorants May Harm Your Hormone Health – Learn why what you put on your skin matters for your thyroid hormone health.
• 11 Environmental and Lifestyle Triggers of Hashimoto’s  – Learn about environmental toxins and nutritional imbalances that can be the trigger for Hashimoto's thyroiditis.

At Paloma Health, our mission is to help you feel your best—not just by treating symptoms but by supporting your whole health journey. We understand that thyroid and hormonal health are influenced by factors beyond what’s happening inside your body. Factors in your environment—from chemicals in everyday products to seasonal exposures like chlorine and pesticides—can quietly disrupt your thyroid function and hormone balance.

That’s why our care goes beyond prescriptions. We make thyroid testing easy and convenient with our at-home comprehensive test kit. And we’re here to keep you informed, aware, and empowered to make choices that support your well-being. Whether you’re navigating hypothyroidism, Hashimoto’s, perimenopause, menopause, or hormonal weight changes, we believe knowledge is one of the most powerful tools you have.

Our team stays up-to-date on the latest research and shares it with you—so you can take control of your health with confidence.

Are you curious about how Paloma can support your health? Learn more about becoming a Paloma patient here.

• Chlorine exposure from pools can interfere with iodine uptake in the thyroid, increasing the risk of hypothyroidism.
• Chemical sunscreens often contain endocrine disruptors; mineral sunscreens, such as zinc oxide and titanium dioxide, are safer alternatives.
• Bug sprays containing synthetic chemicals may include hormone-disrupting additives; use them sparingly and wash them off after application.
• Conventional deodorants may contain aluminum, parabens, and phthalates, all of which are linked to hormonal imbalance; therefore, natural alternatives are recommended.
• Fireworks release perchlorate, a chemical that blocks iodine absorption and can disrupt thyroid hormone production.
• Adequate iodine and selenium intake is vital to counteract environmental exposures and support healthy thyroid function.