12 Surprising Things That Can Make You Sick Even in the Summer

Yes, vitamins are good for you, but like anything else, it's possible to overdo it. Instead of food poisoning or the flu, too much vitamin D might could be the cause of nausea and vomiting, according to the Mayo Clinic. Too much vitamin C can cause similar issues, plus heartburn, headaches, and insomnia — so keep it to the recommended dosage your doctor gives you.

Look down at your nails right now. Chances are, you've got at least a couple specks of dirt or grime gathered under there. That debris can easily spread to anything you touch, including your food. Keeping them clean by either trimming them short or investing in a cheap nail brush ($5.50 for 4 pack, Amazon) is the best way to keep those germs from getting to you. 

If you keep your toothbrushes perched in a cup on your sink, you might want to think of relocating them. The American Dental Association warns this makes them vulnerable to germ exposure and recommends keeping them tucked away in a cabinet. You might think putting a cover on them is the answer, but that only traps moisture and makes them more likely to have microbial growth. You can also rinse them in mouthwash to remove any lingering bacteria before brushing.

Anything we touch on a regular basis is going to be vulnerable to ickiness. One study from the UK found more than 3,000 germs per square inch on the average computer keyboard. When was the last time you gave yours a good wipe down? Just be sure it's powered off before you disinfect!

Think about how many people use an ATM on an average day. Each one of them is leaving traces behind, including germs that can get you sick. You can use a tissue to push the buttons, wash your hands quickly after using them, or carry hand sanitizer to help minimize your exposure.

We often forget about these when it comes to doing the dishes, especially if you rely on an electric can opener to make the job easier on you. But traces of food from everything you open gets left behind on those blades, and need to be washed away to avoid bacteria and other germs from growing and passing along to your meals.

We use sponges to clean up messes, especially food-based ones, so it makes sense they would be prone to hoarding some nastiness. Luckily, the US Department of Agriculture recommends some super easy ways to get rid of those germs: microwaving for one minute or tossing them in your dishwasher for a hot drying cycle. Each method removed 99.9 percent of the bacteria held inside a regular sponge.

Even if you manage to avoid stepping in something particularly gross (like while taking your dog for a walk to do his "business"), your shoes pick up tons of yucky germs, pesticides, and other toxins. The best way to avoid those spreading around your home is to simply take your shoes off before walking in or at the door.

According to a study from the American Society for Microbiology, microbiomes that exist naturally in water love to make themselves at home in our shower heads. This is especially common in metal ones and can lead to issues like lung infections. Switching to a plastic shower head or washing your metal one every time you clean the tiles will help make sure you avoid catching anything while bathing.

Along with the hand of everyone else who went shopping before you, those carts see a variety of foods, dirty purses, and germy paws of kids sitting in the front. If your grocery store doesn't provide wipes, you might want to bring your own.

If you think we touch our keyboards a lot, think about how much more often you check your phone. And do you bring it with you while using the bathroom? That's exposing it to even more potential bacteria and germs that might be passed onto your the next time you check a message or answer a phone call. You can curb this by giving it a regular swipe with antibacterial wet wipes.

If it seems like your seasonal allergies last all year long, you might actually be an allergic reaction to dust mites that gather in your pillow cases. Along with regularly washing and drying your sheets, you should consider investing in a pillow cover like the Eco Living Friendly Evolon Allergy Pillow Protector ($8.99, Amazon).