There’s fungus among us. There’s a wide variety of fungi that live on our skin and in our bodies. If that sounds gross, just know that it’s normal. Most of the time, you’ll have no idea it’s there. Why? Because helpful bacteria in the neighborhood keep that fungus from growing out of control. These organisms are all part of what’s called your microbiome.

Unfortunately, taking antibiotics, certain medications for asthma and autoimmune disorders such as rheumatoid arthritis and lupus, and even pregnancy can upset the balance. They kill the good-for-you bacteria and allow the fungi to have its way. The result? A fungal infection, or mycosis. That will make your life a lot less pleasant. We’re talking uncomfortable skin conditions like athlete’s foot and jock itch, as well as vaginal yeast infections and thrush, which affects your mouth and throat.

Enter clotrimazole

Clotrizamole (Clotrim, Cruex, Lotrimin), an antifungal medication, stops the growth of the fungi that causes the infection. It does this by breaking through the fungi’s protective outer layer and halting the production of a substance called ergosterol, which the organisms need to survive. This allows your body’s bacteria to reset the balance that helps protect you from these infections in the first place.

The medication is widely regarded as safe. “Clotrimazole has been around a while, and it’s well known,” says registered pharmacist Mark McCurdy, owner of Mark’s Pharmacy in Cambridge, Nebraska. He adds that side effects are rare, as are allergic reactions to the drug. However, he does emphasize that it has to be used correctly.

“When I talk to people with athlete’s foot or some other type of fungal infection, I tell them they’re probably looking at about four weeks to completely clear it,” says McCurdy. “You want to keep using it for a few days after the infection clears to make sure it’s fully gone.”

On drugstore shelves, you’ll see it sold as a topical cream that you rub into your skin where the infection has set up residence. You’ll likely need to apply it twice a day, in the morning and evening. Make sure to wash your hands as well as the infected area before using it. Apply just enough to cover the trouble spot or spots. Then wash your hands again; you don’t want to get the cream in your eyes or mouth.

“People try to goop it on, but that’s not necessary,” says McCurdy. “Just a thin layer will do. If the area’s really greasy or you see a lot of cream after applying it, you’ve probably used too much.”

Common conditions treated by clotrimazole

Before we get into specifics, one important reminder: Make sure you actually have one of these conditions before you pick up a tube at the drugstore. Yes, that means get your suspicious symptoms verified by your doctor or pharmacist. Also important to note: These infections can be contagious both to other people and other parts of your body. That makes prompt treatment even more important.

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Ringworm Despite its name, this common fungal infection does not—repeat, not—involve worms of any kind. It gets its name from the ring-like pattern it can form on your skin. About 40 types of fungi can cause ringworm, and the infection goes by different names depending on where it occurs on your body.

  • Athlete’s foot (aka tinea pedis): This type of ringworm mostly settles in between your toes and causes a scaly rash accompanied by itching, burning and stinging. Sweaty feet create the ideal environment for this infection—because fungi love warm, moist settings. Once you finish your four-week course of clotrimazole, make sure to keep your feet dry. Avoid damp socks and tight-fitting shoes. If it doesn’t clear up in a couple of weeks, see your doctor.
  • Jock itch (aka tinea cruris): This infection is common in men than women because of the toasty environment that can develop between the scrotum and thighs. Jock itch causes a similarly red and unpleasant rash as athlete’s foot. Clotrimazole can treat it in about two weeks, and you can keep it from coming back by keeping the area dry. Make sure to towel off thoroughly after showering and exercising.

Thrush (aka oropharyngeal candidiasis): This type of fungal infection occurs in your mouth and throat and can cause soreness, loss of taste and white patches that look like cottage cheese. Fortunately, your doctor can prescribe clotrimazole lozenges. “You suck on it and it distributes the antifungal medication around your mouth,” says McCurdy. Treatment takes 10 to 14 days. Good oral hygiene (brushing, flossing and regular trips to the dentist) can help prevent thrush. Thrush can also affect nursing moms (causing painful, red, cracked nipples) and their babies, who experience oral symptoms. In some cases, clotrimazole cream can be applied to the nipples. Talk to your doctor and pediatrician. It’s important that both mom and baby be treated to prevent passing the infection back and forth.

Vaginal yeast infections (aka candidiasis): Like thrush, this is a fungal infection caused by the yeast candida. It causes itching and burning in the vagina and vulva. Sometimes, you may see a white discharge. Vaginal clotrimazole cream can be inserted into your vagina and spread on the skin outside of it as well. Tablets that can be inserted into the vagina are also available. Fortunately, the course of medication is a short one compared to other fungal infections: usually 3 days to a week. Once it’s cleared, you can help prevent a recurrence by keeping your vulva clean (that means using soap and water, not douching) and wearing clothes that allow air to circulate to keep things dry. Pro tip: If this is the first time you’ve had symptoms like itching, talk to your doctor before you treat yourself.