Spoiler alert: this is a semi-gross topic.
If you have worn the same pair of earrings without cleaning them for a few days, you may have noticed that an odor develops. If this has happened to you, you are not alone.
It also isn't something that should cause you to worry. It is totally normal (albeit kind of gross), but it does not mean that you have an infected ear piercing or that you are reacting to your earrings.
The smell comes from naturally occurring oil, bacteria, and dead skin cells. Your ear piercing sites are the perfect breeding ground for this mixture. Oil, sweat, bacteria, and dead skin cells can all easily be trapped there and quickly start to smell.
If you sweat a lot, work out with your earrings in, don't regularly wash your earrings, and/or wear your earring backs very close to your ear, you are even more likely to experience this smell.
There are a few ways you can avoid getting this funky earring smell. First of all, take your earrings out when you exercise so that sweat does not get trapped in your piercings. Second, take your earrings out when you shower. Third, wash your piercings and earrings with gentle soap and water or a saline solution a few times a week. Make sure to dry off your earrings and your piercings after cleaning them.
For more advice on how to properly care for ear piercings, read this blog post.