You’ll wear 100% cotton clothing inside a hyperbaric chamber, with no synthetic fabrics, no jewelry, and no petroleum-based personal care products on your skin. Most facilities provide cotton scrubs or a gown, so you won’t need to bring your own outfit. The restrictions exist because the chamber is pressurized with pure oxygen, which makes nearly everything more flammable than it would be in normal air.
Why Clothing Rules Are So Strict
A hyperbaric chamber delivers oxygen at pressures up to two or three times normal atmospheric pressure. In that oxygen-rich environment, materials that would never catch fire under everyday conditions can ignite from something as minor as a static spark. The FDA specifically warns that wool and synthetic materials generate more static electricity than cotton, making them a fire hazard inside the chamber. Even standard hospital linens are usually prohibited because they’re typically a polyester-cotton blend, and that small percentage of synthetic fiber is enough to increase static risk.
This is why facilities are strict about what goes in. It’s not bureaucratic caution. Fires in pressurized oxygen environments are fast, intense, and difficult to escape.
What You’ll Actually Wear
Most clinical hyperbaric centers will hand you a set of 100% cotton scrubs or a cotton hospital gown when you arrive. Some facilities ask you to change into these on-site, while others may let you wear your own clothing if it meets the requirements. If you’re wearing your own clothes, stick to 100% cotton from head to toe. That means cotton underwear, cotton socks, and a cotton top and bottom. No polyester, nylon, spandex, rayon, or fabric blends.
Check the tags on your clothing before your appointment. Many items that feel like cotton contain a small percentage of synthetic fiber for stretch or wrinkle resistance. If the label says anything other than 100% cotton, leave it at home.
Items You’ll Need to Remove
Before entering the chamber, you’ll be asked to remove:
- Jewelry and watches. Metal items can create sparks or become uncomfortable under pressure changes.
- Hearing aids and electronic devices. The FDA flags electrical and static-generating devices as potentially prohibited. Batteries can malfunction or pose ignition risks in a high-oxygen environment.
- Underwire bras. The metal wire is a concern. A cotton sports bra or wireless bra is a common alternative.
- Wigs and hair extensions. Many contain synthetic fibers or adhesives that are flammable in oxygen-enriched air.
- Glasses with certain frames. Metal frames are typically fine, but some facilities prefer you remove them. Plastic frames made of petroleum-based materials may be restricted depending on the center.
Contact Lenses and Pressure
Soft contact lenses are generally safe to wear in a hyperbaric chamber. Rigid gas-permeable lenses are a different story. Research from the Defense Technical Information Center found that gas bubbles form rapidly under rigid lenses during pressure changes, even at relatively mild depths. These bubbles cause localized swelling of the cornea’s outer layer. Wearers in the study couldn’t feel the bubbles forming, but the physical effects on the cornea were measurable.
If you wear rigid gas-permeable contacts, switch to soft lenses or glasses for your treatment sessions. If you wear standard soft contacts, you’re likely fine, but mention them to your technician so they can confirm your facility’s policy.
Skin Products and Cosmetics to Avoid
Anything petroleum-based on your skin is a serious fire risk. A study examining skin care products in hyperbaric settings found that products containing petrolatum, mineral oil, paraffin, or paraffin wax had a heat of combustion equal to or exceeding that of gasoline. That’s not an exaggeration. The energy these products release when ignited in an oxygen-rich environment is genuinely comparable to fuel.
By contrast, silicone-based, petroleum-free products scored up to 25 times safer on acceptability indexes used by hyperbaric safety researchers. Before your session, skip the following:
- Lotions and moisturizers containing petroleum jelly, mineral oil, or paraffin
- Makeup and foundation, especially oil-based formulas
- Hair products like gels, sprays, and oils
- Deodorant, particularly aerosol or petroleum-based sticks
- Perfume and cologne
- Nail polish and nail polish remover (acetone is highly flammable)
- Lip balm containing petrolatum or beeswax
If you need moisturizer for medical reasons (wound care, dry skin conditions), ask your hyperbaric team which specific products are approved. Water-based or silicone-based options exist that are chamber-safe.
Wearable Medical Devices
Insulin pumps, continuous glucose monitors, and similar wearable electronics pose unique challenges. The pressurized, oxygen-rich environment can interfere with device electronics, and the devices themselves may contain batteries or components that are fire risks. Most facilities will ask you to remove insulin pumps and CGMs before entering the chamber.
If you rely on an insulin pump, work with your treatment team ahead of time to plan how you’ll manage your blood sugar during sessions, which typically last 90 minutes to two hours. Removing the device for that window requires a plan, not a last-minute decision. Pacemakers and other implanted devices are a separate consideration. These don’t need to be removed, but your hyperbaric physician will review their compatibility before your first treatment.
What to Expect on Your First Visit
Arrive with a clean face and clean skin. Don’t apply any products after your shower. Wear loose, comfortable clothing that you don’t mind changing out of, since you’ll likely swap into facility-provided scrubs anyway. Bring a bag for your personal items: phone, wallet, keys, jewelry. These will stay in a locker or with a staff member outside the chamber.
Inside the chamber, you’ll have limited entertainment options since most electronics are prohibited. Some multiplace chambers (the walk-in kind that treat several people at once) allow books or magazines, though the paper must be approved. Monoplace chambers (single-person tubes) often have a window and intercom, and some facilities pipe in music or video through external speakers or screens.
The clothing restrictions can feel overly cautious for something that looks like lying in a tube for an hour. But hyperbaric oxygen therapy involves a genuinely unusual environment where normal fire safety assumptions don’t apply. Following these guidelines is straightforward once you know what to expect, and your facility will walk you through everything before your first session.