When to toss common household items

The ritual of deep cleaning doesn't just clear the cobwebs from your ceilings (and your head); it's essential for good health, too. But that involves knowing when to pitch everything from medication to your smoke alarm. This room-by-room guide outlines some surprising expiration dates.

When to toss: Every year.

Why: Hair and body oils will have soaked into a pillow's fabric and stuffing after a year of nightly use, making it a breeding ground for odor-causing bacteria and allergy-triggering dust mites. Using protectors can double the life of your pillows.

When to toss: After five to 10 years.

Why: A good mattress lasts nine to 10 years, according to the National Sleep Foundation, but consider replacing yours more often than that if you don't sleep well. A study at Oklahoma State University found that most people who switched to new bedding after five years sleep significantly better and have less back pain.

When to toss: After 10 years.

Why: After a decade, a unit's sensors become less sensitive, putting you at greater risk from smoke or fire should a blaze erupt. Test smoke alarms monthly and replace batteries with new ones every year. To safeguard your family, install alarms on every level of your home, in bedrooms and outside all sleeping areas. Scary stat: One-fifth of U.S. homes have smoke alarms that don't work.

Why: With proper maintenance, including annual servicing, a room or central air conditioner can run 15 years or more, said Bill Harrison of the American Society of Heating, Refrigerating and Air Conditioning Engineers. Check the filter at least every six weeks, particularly in humid weather. "If dirt covers the filter so you can't see the original material or view light through it, clean it or buy a new one," he said.

When to toss: If there's no expiration date, throw after two years.

Why: Independent tests find that most nutritional supplements are good for three years if stored in a cool, dry place, said William Obermeyer, vice president for research at Consumer­Lab.com. Without an expiration date, there's no way to tell how long a bottle sat in a warehouse before you bought it, so go with a two-year life span to play it safe.

When to toss: Every 10 years.

Why: Portable extinguishers lose pressure over time and become ineffective whether or not they've been triggered, said Lorraine Carli, national spokeswoman for the National Fire Protection Association. If your extinguisher is rechargeable, have it serviced every six years or when the pressure is low.

Why: "Filters that make health claims like lead removal are designed to provide a margin of safety in case they're not changed on time," said Rick Andrew, operations manager at NSF International, a Michigan-based company that tests filters. This applies to most drinking water purifiers, including models from Culligan, Brita and PUR. Those equipped with expiration indicators, such as trigger lights, last 20 percent longer than their recommended life, so a filter certified to clean 100 gallons actually purifies 120.

When to toss: If properly cleaned, keep them indefinitely.

Why: How you sanitize the board — and not its age — is what kills bugs such as E. coli and Salmonella. "The decision to replace one is ultimately based on when you think it looks too beat up," said Brenda Wilson, an associate professor of microbiology at the University of Illinois at Urbana-Champaign. Even a board with deep cracks or grooves is safe if it's sanitized after each use: Wash the board with detergent and hot water; then rinse and flood with a solution of one part full strength white vinegar to 4 parts water and let it sit for 5 minutes. Rinse with clean water, pat with a clean towel and air dry.

When to toss: After three months.

Why: "Once the seal is broken, germs can contaminate bottles that are left uncapped or that lack a backflow device, increasing your risk of infection," said Louise A. Sclafani, an associate professor of ophthalmology at University of Chicago Hospital. Get a new case every three months, too.

Why: The applicators used to apply mascara, liner and shadow are repeatedly exposed to bacteria in the air and on your lashes; after six months of everyday use, they can overpower the products' preservatives, said John Bailey, chief scientist at the Personal Care Products Council. Liquid products that don't touch the eyes, such as foundation, can be used for up to two years; dry face products such as powder and lip items are generally formulated to last at least three years.

When to toss: After one year.

Why: Beyond a year, the antibiotic probably is still good, but the chemical mix in the ointment might start to go bad, which makes the product less effective.

When to toss: Every three or four months.

Why: The American Dental Association recommends a three- to four-month rotation because frayed and worn bristles don't clean as well, leaving teeth more vulnerable to decay.

Why: Most medicated shampoo will stay effective at least that long if there isn't an expiration date. Adding water to an almost empty bottle to get the last bit from the bottom dilutes preservatives and makes them less effective, so toss the remainder after several days.

When to toss: Not until the bottle is empty.

Why: "Rubbing alcohol practically lasts forever," said Abigail Salyers, a professor of microbiology at the University of Illinois at Urbana-Champaign. Even after exposure to air, the alcohol/water solution remains stable for years, if not decades, and the alcohol kills any microbes that might get into the bottle.