Costco is known for offering great deals on just about everything—from bulk groceries to household essentials—but when it comes to clothing, it’s not always as straightforward. While Costco carries a range of name-brand and in-house Kirkland Signature clothing, not all of it is created with health in mind.

What many people don’t realize is that conventional clothing can be a hidden source of toxins, exposing your skin to harmful chemicals through synthetic fabrics, chemical dyes, and fabric treatments. The materials you wear daily—especially if they contain synthetic fibers—can introduce endocrine-disrupting chemicals, allergens, and skin irritants that slowly make their way into your body.

That doesn’t mean Costco is a total no-go for clothing. If you know how to read labels and choose wisely, you can still find some good-quality, lower-toxicity options without breaking the bank. The key is knowing what to look for and what to avoid. Here’s how to shop smarter at Costco’s clothing section while keeping your health in mind.

Why Clothing Materials Matter

Before jumping into the best and worst clothing picks at Costco, it’s important to understand why fabric choices matter in the first place. Clothing is in constant contact with your skin, the body’s largest organ. Synthetic materials like polyester, spandex, and modal are often made using petroleum-based chemicals that don’t just stay in the fabric—they can leach out over time, especially when exposed to heat, sweat, or friction.

Some of the biggest concerns with conventional clothing materials include:

• Endocrine disruptors in synthetic fabrics – Many synthetic fibers, including polyester and spandex, are made with chemicals like BPA, phthalates, and formaldehyde that have been linked to hormone disruption and reproductive health issues.
• Toxic solvents in bamboo viscose and modal fabrics – While bamboo and modal sound like natural materials, they undergo harsh chemical processing that uses toxic solvents like carbon disulfide. These chemicals can leave residues in the fabric, which may be absorbed by the skin.
• Chemical dyes and fabric treatments – Many mass-produced clothes are dyed with synthetic, petroleum-based dyes that can leach into your skin over time. Flame retardants, wrinkle-resistant treatments, and waterproof coatings can also introduce unnecessary chemicals to your body.
• Microplastic shedding – Synthetic fibers like polyester and nylon shed microplastics when washed, which not only contribute to environmental pollution but can also accumulate in your body over time.

What to Buy: Low-Tox Options That Make the Cut

Despite these concerns, there are still some decent clothing options at Costco that minimize exposure to synthetic materials. While it’s not always possible to find 100% natural fiber clothing, choosing blends that contain mostly natural materials can significantly lower the toxic load. Here are a few solid picks:

Orvis Shorts: 82% Cotton, 18% Lyocell Bamboo

Orvis is known for producing high-quality, durable clothing, and these shorts are no exception. The fabric blend here is relatively low on the toxicity scale, making them a good choice for everyday wear.

• Why they’re a good choice: Cotton is a natural, breathable material that doesn’t trap heat or moisture against your skin like synthetic fabrics do. Lyocell bamboo is also one of the safer bamboo-based fabrics since it’s made using a closed-loop process that limits chemical exposure.
• What to watch for: While lyocell is a safer alternative to viscose bamboo, it’s still processed to some degree. If you’re sensitive to chemically treated fabrics, you may want to stick with 100% cotton or linen options.

Slack Pants: 98% Cotton, 2% Spandex

For those looking for a comfortable and breathable pant option, these are a solid pick. With 98% cotton, the fabric is mostly natural, and the minimal amount of spandex is likely just in the waistband, where it won’t be in direct contact with most of your skin.

• Why they’re a good choice: The high cotton content keeps these pants breathable, reducing the risk of skin irritation and overheating. The natural muted colors are also a bonus, as they likely contain fewer synthetic dyes compared to brightly colored synthetic fabrics.
• What to watch for: While 2% spandex is minimal, keep in mind that any synthetic fiber can still release microplastics when washed. Washing these in a garment bag on a cold cycle and air drying can help reduce fiber shedding.

100% Cotton Jeans or Levi’s

Denim is one of the better fabric choices when it comes to reducing toxin exposure, especially if you stick with 100% cotton options. Costco often carries Levi’s jeans, which tend to be made with mostly cotton and contain only a small percentage of elastane (usually around 1% or 2%).

• Why they’re a good choice: Cotton denim is durable, breathable, and free from synthetic materials that trap heat and moisture. Because Levi’s uses minimal stretch fibers, they’re less likely to contain high amounts of elastane or polyester.
• What to watch for: Some jeans are treated with synthetic dyes, so if you’re sensitive to chemical treatments, wash them a few times before wearing them. Also, avoid options labeled as “wrinkle-resistant” or “moisture-wicking,” as these often have added chemical coatings.

What to Avoid: High-Tox Clothing to Skip

Not all blends are created equal. Some materials may sound natural but undergo intensive chemical processing that makes them far from healthy. Here are a few clothing items you should steer clear of at Costco.

Slack Pants: 91% Modal, 8-9% Spandex

At first glance, modal might seem like a good option. It’s derived from natural wood fibers, often birch or beech trees. However, the way it’s processed is where the issues come in.

• Why they’re problematic: Most modal fabric is treated with toxic solvents to break down the plant fibers into a usable textile. This process leaves behind chemical residues that can be absorbed by the skin, particularly when sweating.
• Better alternative: If you find modal clothing, look for Tencel Modal, which is made using a safer, more controlled process that reduces chemical exposure.

How to Shop Smarter for Clothing at Costco

If you want to minimize your exposure to synthetic materials and unnecessary chemicals, here are a few guidelines to follow when shopping at Costco (or any other big-box retailer):

• Prioritize natural fibers. Cotton, linen, and wool are the best options for reducing toxin exposure. Avoid anything labeled as polyester, acrylic, rayon, or nylon.
• Read the blend percentages. A small amount of synthetic material (1-2%) is usually okay, especially if it’s in the waistband or stitching rather than the main fabric. But avoid anything that’s majority synthetic.
• Be mindful of dyes. Bright, synthetic dyes can contain heavy metals and other harmful chemicals. Stick to lighter, muted colors when possible.
• Avoid wrinkle-resistant or moisture-wicking fabrics. These are often treated with chemical coatings that can release toxins over time.
• Wash new clothes before wearing them. This helps remove residual dyes, chemical treatments, and microplastics that may be lingering in the fabric.

Final Thoughts

Building a non-toxic wardrobe doesn’t mean you have to shop exclusively at high-end organic retailers. With a little awareness and smart label reading, you can find better clothing options—even at Costco. By prioritizing natural fibers, avoiding heavily processed synthetics, and being mindful of chemical treatments, you can stock your closet with clothes that support your health rather than exposing you to unnecessary toxins.