Living with celiac disease means following a gluten-free diet to improve quality of life. A general rule is to read all food product labels, but there are also less obvious sources of gluten that often go overlooked. Many everyday nonfood items could exacerbate celiac disease symptoms, leading to digestive problems.

Many people who avoid gluten—a protein found in wheat, barley and other grains—for medical reasons question the validity of products labeled “gluten-free.” But a Food and Drug Administration (FDA) study did find that products given this label are in fact gluten-free. However, other terms, such as “no gluten ingredients” and “made without gluten,” do not abide by FDA labeling regulations. They suggest that the products could be made in a shared facility or that the ingredients are not sourced from gluten-free manufacturers.

Food labels usually say whether the products contain gluten, but there is rarely information with unexpected sources of gluten, like cosmetics and toiletries. For example, earlier research has found that among 10 leading makeup companies, none actually provided any information on whether their products contained gluten. Although gluten can’t be absorbed through the skin, it’s possible to ingest a small amount of it via cosmetics, especially if used on the hands or mouth.

Below are seven surprising sources of gluten that celiac patients should avoid, from medications to play dough.

Medications

There are several drugs that contain gluten, including certain dosages of Tekturna HCT (an antihypertensive drug); Sanctura (used for overactive bladder); and Doryx (an antibiotic). Whether a prescription contains gluten is specific to each medication and cannot be generalized to an entire class of drugs. Andrea Langston, a Buffalo, New York, integrative nutritionist with celiac disease, explains that gluten content greatly depends on the manufacturer.

“Many medications are probably gluten-free, as they do not use any gluten-containing ingredients, but they could be cross-contaminated and are not tested to know if they are truly gluten-free,” Langston tells Newsweek.

She recommends speaking with a pharmacist, who can check the ingredients and reach out to the manufacturer to see whether the product is gluten-free, likely gluten-free or not gluten-free.

Langston adds, “It is also important to verify the gluten-free status of your medications periodically because formulations can change without notice to the consumer.”

Vitamin Supplements

Gluten can act as a glue or binder in several products, like vitamin supplements. Because it’s relatively cheap, it can be used liberally. Professional brands tend to be more transparent about the ingredients and potential allergens, according to Langston, but they may cost more. A good rule of thumb is to read the ingredients listed and also look for products advertised as gluten-free.

Orthodontic Retainer

Gluten is a common additive in plastics that can be found in orthodontic retainers and other dental products. In a 2013 study published in Clinical Pediatrics, a 9-year-old girl, who was under a gluten-free diet did not show improvement in her symptoms until her retainer was removed. The researchers suspect the retainer was to blame, as it contained methyl methacrylate—a compound used to create polymers in several plastics, including retainers.

“We can be extremely diligent with diet, but if we aren’t considering all aspects our environment, we could be missing out on vital information,” says Langston.

Sunscreen

Several types of sunscreen may contain ingredients that come from wheat, such as vitamin E when it is derived from wheat germ oil. Langston explains that gluten is used as an emulsifier and stabilizer to create the creamy texture that is found in products like sunscreen. A majority of sunscreen brands may contain gluten, and while some do not, they may manufacture it in a facility that also processes wheat and gluten materials on the same machinery.

Beauty Products

As previously discussed, any beauty product can contain gluten, ranging from lotion to even hand sanitizers. The areas on the body where these products are being used, such as the lips or hands, can potentially cause damage to the gastrointestinal tract, as there’s a possibility they may be ingested. If you have celiac disease, Langston recommends opting for a gluten-free sanitizer, especially before you eat.

Similarly, lipstick and lip balms are important because of where they are applied. “It is vital to make sure they are gluten-free because the mouth is the beginning of the digestive system,” says Langston. However, it may not be as important to purchase gluten-free products such as mascara, depending on your level of sensitivity and comfort.

Pet Food

There is a risk from pet food when it comes to gluten exposure. The most obvious way to be exposed is if you’re serving the food to your pet and do not wash your hands afterward. Anna Baker, a nutrition expert at Nutrition Journey, explains that if you suffer from dermatitis herpetiformis (DH)—a skin manifestation of nonceliac wheat sensitivity—gluten in your dog food can be transferred to your skin through licking.

But it is not all bad news. “Those who have celiac disease but not DH are only at risk if the dog licks close to or in the mouth and a trace of the gluten is digested,” Baker tells Newsweek.

Play Dough

Another surprising nonfood item that contains gluten is play dough. This is risky for those with celiac disease, especially kids who like to put everything in their mouths. Although they may not eat play dough, it can get on their hands and be easily transferred to the mouth.

The best way to avoid gluten if you have celiac disease is to look for “gluten-free” labels, read the list of ingredients and contact the manufacturers for clarity.