The next time your eyes water and breath labors, don't automatically blame the trees outside. It could be your air freshener or the food dye in your cereal. “Most household products aren't tested to see if they cause lung reactions or asthma,” says Kenneth D. Rosenman, MD, chief of the occupational and environmental medicine division at Michigan State University in East Lansing. “Furthermore, manufacturers aren't required to list any ingredients except disinfectants.” As a result, your home likely contains dozens of contaminants that can cause anything from itchy skin to asthma. Follow this expert advice on how to identify and avoid common allergy-inducing toxins.

Toxins In your food:

Sulfites

According to the FDA, 1 in 100 people are sensitive to sulfites, which were banned in 1986 for use on supermarket produce and in restaurant salad bars. But these sulfur-based compounds are still used to inhibit bacteria growth and preserve flavor in wine, grape juice, soup mixes, dried fruit, and canned vegetables. Symptoms of sensitivity — such as skin redness, tingling in extremities, and airway constriction — usually present within minutes of consuming sulfites. Asthmatics are five times more likely to suffer an adverse reaction.

How to avoid them: Manufacturers must indicate on labels if a product contains at least 10 parts per million sulfites. Avoid dried fruits that look especially colorful, a sign of preservatives. Also, choose USDA certified organic wine, which cannot contain added sulfites.

Monosodium glutamate (MSG)

A flavor enhancer found in Asian food, canned vegetables, soups, and processed meats, MSG stimulates taste buds and adds a salty flavor. But it can also exacerbate true allergies, as well as cause headaches, upper-body tingling, numbness, and burning sensations.

How to avoid it: Ask for MSG-free meals at Asian restaurants. Foods labeled “No MSG” might still contain glutamate derivatives like hydrolyzed plant protein, yeast extract, and autolyzed yeast, so read ingredients lists carefully.

Toxins in your home:

Synthetic fragrances

They may smell sweet, but when it comes to your health, synthetic fragrances stink. A 2007 study of six fragranced consumer products discovered that the cleansers emitted nearly a hundred different volatile organic compounds (VOCs), chemicals released as gas. These included acetaldehyde and 1,4-dioxane, which cause immediate eye, skin, and airway irritation. And weekly use of common glass cleaners, furniture sprays, and air fresheners has been linked to a 30 percent to 50 percent increased risk of adult asthma. Plug-in air fresheners, in particular, emit a constant cloud of VOCs called terpenes, a class of pine- or lemon-scented plant oils. While not themselves toxic, terpenes off-gas formaldehyde when mixed with ozone, resulting in watery eyes, wheezing, and inflamed airways. That said, current consumer laws don't require labels to list VOCs or fragrances — even if they cause respiratory problems.

How to avoid them: Avoid using ionizing air purifiers, which can produce indoor ozone, a molecule that is highly reactive when placed in contact with other substances — especially air fresheners that emit terpenes. Rather, neutralize odors with Boston ferns, bamboo palms, and spider plants, which also absorb toxins such as formaldehyde and benzene. Instead of sprays and aerosols, use essential oils diluted in water to reduce your exposure to airborne chemicals.

Particulates

Conventional and scented candles generate particles of soot and benzene — the same pollutants found in diesel exhaust — according to the EPA. Plus, although lead in candles has been outlawed in the United States, many imported candles still contain lead-stiffened wicks. “Even if these tiny irritants aren't immediately noticeable, repeated low-level exposure can develop into a chemical allergy where even a brief exposure can trigger a rash or coughing fit,” says Rosenman.

How to avoid them: Search out natural, soy-based candles, which burn cleanly and don't use leaded wicks.

Learn about safe air fresheners and how to use essential oils here.

Toxins on your skin:

Sodium laurel sulfate (SLS)

Reactions — redness, swelling, and burning sensations — look the same whether caused by chemical irritants or allergy. Irritants, however, provoke an immediate reaction, while allergies can require weeks of constant exposure to develop. This foaming and cleansing detergent found in shampoo, body wash, and toothpaste may cause instant irritation to the skin, eyes, and mucous membranes and can eventually become an allergen. And because your skin and your airways aren't entirely separate, SLS may trigger respiratory symptoms as well. Similar chemicals found in foaming bath products include diethanolamine, monoethanolamine, and triethanolamine.

How to avoid it: “If it bothers you, reduce your exposure,” says Richard Honsinger, MD, an allergy specialist in Los Alamos, New Mexico. Choose products that contain natural foaming agents, such as coconut-derived lauric acid.

Formaldehyde

The same toxic preservative used in embalming is added to most nail polishes and mascaras to inhibit bacteria growth. Whether it's applied to wounded or broken skin (think cracked cuticles) or inhaled as a gas (wet nail polish), formaldehyde is responsible for the largest proportion — more than 25 percent — of cosmetic-instigated contact dermatitis and allergic reactions, according to a recently published study. Skin reactions can occur on eyelids, neck, and face, while fumes irritate eyes, nose, and throat.

How to avoid it: Choose nail polishes and removers that use gentler polyester resins instead of formaldehyde-releasing preservatives such as tosylamide formaldehyde, quaternium-15, diazolidinyl urea, and DMDM hydantoin.