Every time a new month rolls around, it's out with the old and in with the new. Of course, we're a big fan of using something until it wears out, but there are just some items that you should replace often. Here they are:
1. Scratched nonstick pans
If you see any scratches in your nonstick pans, it's time to throw it away or invest in a cast iron pan. The coating can come off when you're cooking, and chemicals can leak into your food.
You should replace your toothbrush regularly. The American Dental Association says you should get a new one every three to four months  to avoid the buildup of bacteria.
Makeup should be replaced often, because if it's too old, it can irritate your skin or even cause infections. Here are some guidelines for when to replace what .
4. Contact lens case
You should buy a new contact lens case every three months to reduce the risk of an infection.
5. Kitchen sponge
One University of Arizona study found that a kitchen sponge can be up to 200,000 times dirtier than a toilet seat . Before you start gagging, just remember to replace it regularly. Some people trash sponges every after cleaning, but others throw them away every one to two weeks or monthly. Remember to clean your sponge after every use by throwing it in the dishwasher with your dishes or nuking it in the microwave for 30 seconds while it's wet. Brushes tend to be more hygienic as they are easy to clean and dry more quickly, so you might want to replace your sponges with brushes.
6. Toilet brush
This should be a no-brainer, but remember to replace your toilet brush regularly. Some people believe in disposing of the brush when it starts looking discolored and grungy, while others believe in getting a new toilet brush about every six months. How long you wait before getting a replacement also depends on how often you use it.
7. Plastic tupperware
Tupperware seems to last forever, but if you have any sitting in your cabinets from 2010, you might want to consider tossing them out. Those made before 2010 can contain BPA, a hormone-disrupting chemical that leaks into food as containers age or get heated.
You might want to replace pillows after 18 to 24 months, as old pillows may have bacteria, dead skin, dust mites soaked into it. These can make allergies worse. However, if you wash and fluff your pillows and use pillow covers, you probably don't need to replace it as often. If you start feeling like the pillow is out of shape and does not provide good support for your neck and head, it's time to replace it.
9. Water filter
You should be changing your water filter regularly — every few months depending on the type of filter. Old and contaminated filters can cause the water to be less clean than the original water.
10. Running shoes
You're supposed to replace your sneakers every 300 to 500 miles . Running in shoes with too much mileage on them can make you more prone to injuries.
The shelf life of sunscreen is three years, but if you really want to play it safe, replace your sunscreen every year. Having sunscreen that's too old may lose its efficacy, which means more exposure to harmful UV rays.
12. First aid kit
You don't have to replace your first aid kit entirely, but you should definitely swap out the items with expiration dates on them. If anything happens, you'll have effective medication on hand to treat the illness or injury.