10 things you need to replace way more often than you probably do

• There are a lot of items you use every day that you may not be replacing often enough.
• The American Dental Association recommends that you replace your toothbrush every three to four months.
• Mascara lasts two to three months, or until it looks clumpy and develops an unusual odor.
• Bras can lose their elasticity and shape after six months of heavy wear.

A lot of items, accessories, and tools that you use every single day have a shelf life and need to be replaced regularly. But chances are you own a lot of things that ought to be swapped out sooner rather than later.
Here are 10 things you need to replace more often than you think.

The American Dental Association recommends replacing your toothbrush every three to four months.

According to the American Dental Association (ADA), you should replace your toothbrush (or the head of an electric toothbrush) once every three to four months.
As Keith Arbeitman, a dentist in New York City, explained in an interview with Business Insider, how often you should swap your toothbrush for a new one depends on how frequently you use it. A telltale sign of wear is when the brush's bristles start to bend, he said.

When stored properly, sunscreen should be tossed after a few years.

Sunscreen is a beach essential, but the protective lotion isn't effective forever.
The Food and Drug Administration (FDA) mandates that sunscreens retain their original strengths for a minimum of three years. Because of this, some brands label their bottles with an expiration date.
If there's no expiration date listed on your bottle, the Mayo Clinic recommends writing the date that you purchased the product on its package. And, per the FDA, you'll want to toss it after three years because you can't be sure if it's still effective or safe.
To make sure your sunscreen lasts for as long as possible, it's best to store it in a cool place away from excessive heat.

You should replace your hairbrush every six months to a year.

Women's Health magazine recommends replacing your hairbrush every six months to a year because, over time, brushes can accumulate build-up from products and matted hair.
"Dirty brushes can make clean hair look dirty, greasy, and weighed down," Tsippora Shainhouse, MD, a board-certified dermatologist in Beverly Hills, California, told Women's Health. "The product debris can irritate the scalp, which can lead to redness, itch, and scale."
Overall, when the bristles begin to separate and cracks appear in the bed of the brush, it's time to get a new one.

It’s ideal to replace your razor blade after five to seven shaves.

The American Academy of Dermatology says to replace your razor blade or throw out your disposable razor after five to seven shaves. This will minimize irritation to your skin because regularly replacing razors can help you avoid using a dull blade.

You should replace sheets every two to three years.

House Beautiful recommends replacing sheets every two to three years. After a while, the fabric will show signs of wear and tear, such as thinning and fading, and the material will begin to feel less comfortable.
If you want to preserve your sheets, you can alternate between two or more sets. When washing them, a cool or warm cycle will be your best bet.

Mascara lasts two to three months.

Makeup shelf-life varies from product to product, but mascara can go bad in a few short months.
Generally, you should chuck mascara after two or three months, or when it becomes clumpy or develops a strange odor.
You should never add water or saliva to your mascara in an attempt to moisten it if it dries out, either, as this can introduce bacteria into the product, per the FDA.

Since kitchen sponges are a breeding ground for bacteria, some microbiologists say you should replace them once a week.

Despite being a cleaning tool, your kitchen sponge could be one of the dirtiest items in your home.
A study published in 2017 in the journal Scientific Reports found that sponges can host a lot of bacteria, including pathogens, which can cause certain illnesses.
The researchers also determined that prolonging the life of cleaning sponges by boiling or microwaving them is somewhat effective, but it won't exactly make them sterile.
For a healthier, cleaner kitchen, it's best to replace sponges every week.

Bras can lose their elasticity and shape after about six months of heavy wear.

Bra shopping can be a drag, but these undergarments won't last forever.
According to Lexie Sachs, a textiles product analyst in the Good Housekeeping Institute, you'll need to replace your bras when they lose their elasticity, which could be in six months from when you purchased them.
"If your bra is no longer stretchy in the straps or back, it won't offer the proper support," she said. Sachs also advises getting rid of old bras if the cups and padding have shifted. If your undergarment has a gap or bulge, it won't provide adequate breast support.
Ultimately, how often a bra lasts depends on how often you wear it. By rotating multiple bras, you can help them retain their elasticity and shape much longer.

Pillows can become flat and absorb a ton of detritus after one to two years.

Pillows provide neck and back support, so it's important to replace them every one to two years, according to the National Sleep Foundation.
Not only do pillows flatten over time, but also they can accumulate dead skin cells and hair, in addition to absorbing body oil. This detritus helps dust mites, a common allergen, thrive.
When pillows become lumpy or stay in half when you fold them, it's probably time to replace them.
And, if you want your pillow to last longer, wash it every six months and cover it with a protectant case.

You should swap out smoke-alarm batteries at least once a year.

Per the US Fire Administration, you should swap out the batteries in your smoke alarm at least once annually and replace the alarm itself after 10 years.

The administration also recommends testing fire alarms once a month to make sure that they work.