Itching, abnormal vaginal discharge, a burning sensation when you pee… sometimes it’s hard to tell whether these are symptoms of a yeast infection or a sexually transmitted infection (STI).

STIs and vaginal yeast infections share many symptoms, making it difficult to tell them apart. However, it's crucial to recognize the differences as they require different treatments. 

If left untreated, both conditions can get worse, but unlike yeast infections, STIs can cause long-term health complications such as pelvic inflammatory disease (PID) and infertility. 

Learning to tell them apart can help you take the necessary steps to seek proper treatment. Keep reading to learn about the difference between a yeast infection and STI. 

What is a yeast infection? 

A yeast infection — also called vulvovaginal candidiasis — is caused by the overgrowth of the fungus Candida. Most yeast infections — up to 90% — are caused by Candida albicans specifically. It's an incredibly common vaginal health issue; up to 75% of women will have a vaginal yeast infection at least once in their lifetime. 

Candida, a type of yeast, naturally lives on our skin in various parts of our body, such as the mouth, throat, and vagina. While it’s normal to have small amounts of Candida in the vagina, it can sometimes grow excessively, leading to a vaginal yeast infection.

Yeast infections are super uncomfortable and can be a nuisance, but unlike STIs, they’re not linked to long-term health complications if left untreated. 

Yeast infection symptoms 

Common symptoms of a yeast infection include:

Is a yeast infection an STD?

It’s important to clarify that while sex can trigger yeast infections, a yeast infection is not a type of STI. Yeast infections aren’t considered an STI because they can show up in people who aren’t sexually active, too. Some common triggers and risk factors for yeast infections are:

  • Taking antibiotics
  • Being on certain kinds of birth control 
  • Douching or using scented feminine products
  • Staying in wet clothes, such as swimsuits and workout attire, for long periods of time
  • Being pregnant 
  • Uncontrolled diabetes  
  • Having a weakened immune system (like in HIV). 
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What are STIs?

A sexually transmitted infection (STI), or sexually transmitted disease (STD), is an infection passed through sexual contact — including vaginal, anal, and oral sex. When someone has a STD, they can give it to a sexual partner during sex. 

In this article, we use the terms STD and STI interchangeably — both terms mean the same thing. STD stands for "sexually transmitted disease," and STI stands for "sexually transmitted infection." While some healthcare professionals prefer to use STI because it carries less stigma, others might be more familiar with the term STD. Regardless of the word used, both refer to infections transmitted through sexual contact.

There are over 30 known sexually transmitted infections and diseases, but some of the most common STDs are: 

Many sexually transmitted diseases are asymptomatic, meaning they don’t usually cause symptoms — or they may only cause mild symptoms. This means that it’s possible to have an STI and pass it to other sexual partners and not even realize it. That’s why it’s crucial to get tested for STIs! If you are sexually active and want to get tested at home, Evvy’s Expanded PCR Panel looks for chlamydia, gonorrhea, and trichomoniasis. 

How to tell the difference between a yeast infection and STI

It can be challenging to tell the difference between a yeast infection, other vaginal conditions (like bacterial vaginosis), and STIs. As tempting as it is to self-diagnose, studies show that only about one-third of people can correctly diagnose themselves with a yeast infection.

Yeast infections and STDs often have similar symptoms, so the only way to tell them apart is by doing an STI test. Screening for a sexually transmitted infection involves going to a clinic where a nurse or doctor will collect a sample with a vaginal swab. Sometimes, they might need to collect a urine sample or do a blood test, too. 

For many STIs — including trichomoniasis, chlamydia, and gonorrhea — you can do an at-home STI test, like Evvy’s Vaginal Health test with the Expanded PCR Panel. 

Symptoms that STIs and yeast infections have in common

Annoyingly, yeast infection symptoms can be similar to those of several STIs. The most common symptoms that STIs and yeast infections have in common are: 

  • abnormal vaginal discharge that may be watery or thick
  • burning or discomfort while peeing (dysuria) or having sex (dyspareunia)
  • pain or tenderness in the genitals and/or lower belly
  • redness and swelling of the vagina
  • itching or burning in and around the vagina.

STI discharge vs. yeast infection discharge

The hallmark symptom of a yeast infection is clumpy, white discharge that looks like cottage cheese. But many STIs can cause abnormal discharge, too: 

  • Chlamydia can cause thick, milky, or watery discharge that might be white or yellow and have an unpleasant smell. Chlamydia discharge can often be confused with a yeast infection, but yeast infection discharge doesn’t usually have a foul odor.
  • Gonorrhea can cause watery or thin discharge that might be green or yellow 
  • Trichomoniasis can cause thin or frothy discharge that might be green, gray or yellow and have a fishy smell.

Yeast infection vs. STI treatment 

Because yeast infections are caused by a fungus (not bacteria), they’re treated with antifungal medications that can be topical (like a cream) or oral (pills).

Your healthcare provider will recommend the best treatment based on the severity of your symptoms and whether you’ve had yeast infections a lot in the past.

For mild yeast infections, you may be prescribed a short course of vaginal antifungal medicine in cream, ointment, or suppository form. Alternatively, you may be given a single oral dose of fluconazole (unless you're pregnant).

You may need multiple oral doses of antifungal medication or a longer course of vaginally inserted antifungal medicines for more severe or frequent infections. 

If the infection is not responding to antifungal drugs, your doctor may recommend other medicines, such as boric acid, nystatin, or flucytosine, which can be taken as a vaginal suppository.

STI and STD treatment, on the other hand, depends on the type of infection.The four most common sexually transmitted infections caused by bacteria are chlamydia, gonorrhea, syphilis, and trichomoniasis. These STIs can usually be treated with a course of antibiotics. In most cases, your doctor will recommend oral antibiotics. Given the rise of drug-resistant strains of gonorrhea, the Centers for Disease Control and Prevention (CDC) now recommends treating gonorrhea with a single intramuscular injection of antibiotics. 

For STDs like herpes and HIV (which are caused by a virus, not bacteria), there are antiviral medications that can help manage the symptoms and slow the virus's progression. Although they can't completely cure the disease, they can make things more manageable. Genital warts are also caused by a virus (called HPV), but unlike herpes and HIV, the treatment for genital warts involves removing the warts from your skin, which can be done several different ways. You can also get an HPV vaccine to reduce your risk of contracting genital warts — just keep in mind that the vaccine can only prevent new HPV infections but doesn’t treat existing HPV infections if you already have it.

In the case of hepatitis B and C, antiviral medications can help fight the virus (and sometimes cure it).  

How to prevent yeast infections and STIs

Yeast infections and STIs are almost a fact of life, and there’s no way to 100% prevent them. That said, there are some steps you can take to reduce your risk.

Steps you can take to prevent yeast infections:

  • Avoid underwear that is too tight 
  • Do not douche or use scented feminine products (including bubble bath, pads, tampons, and soaps/perfumes) 
  • Avoid staying in wet clothes for long periods of time
  • Take a probiotic during/after a course of antibiotics 
  • Wash your sex toys before and after each use.
  • After anal sex, change your condom or wash your sex toy before vaginal penetration. 

Steps you can take to prevent STIs:

  • Use condoms during vaginal, oral, and anal sex
  • Get tested for STIs at least once a year and whenever you have a new sex partner
  • Get vaccinated for hepatitis B and HPV 

FAQs

Does a yeast infection mean you have an STD?

No, a yeast infection isn’t a sexually transmitted disease (STD). Although sex can trigger a yeast infection, you can develop one even if you’re not sexually active. It’s also worth mentioning that although many STDs can cause symptoms similar to those of a yeast infection, they’re two different conditions. 

How do I know if it's a yeast infection or STD?

​​There’s no real way of knowing whether you have a yeast infection or STD simply by looking at your symptoms. The only way to know for sure is to do an STI test. Seeing your healthcare provider if you start experiencing any symptoms is always a good idea. 

Can a yeast infection be mistaken for chlamydia?

Yes, it’s very easy to confuse a yeast infection with chlamydia because they share a lot of symptoms, like itching, burning, and abnormal discharge. Research shows that most people aren’t very good at self-diagnosing a yeast infection, so it’s better to be safe than sorry and do an STI test to be sure. 

Why do I keep getting yeast infections from my boyfriend?

While yeast infections aren’t considered a sexually transmitted infection, it’s possible to get one after having sex. The friction during sex can cause minor damage and tears to the vagina, making Candida more likely to overgrow. The exchange of fluids during unprotected sex can also introduce new pathogens, change your vaginal pH and encourage the overgrowth of Candida. And since men can get yeast infections too (although less frequently than women), there’s always a chance that your boyfriend can pass it on to you.

Can a yeast infection spread to a man?

Technically, yes. A yeast infection can spread from a woman to a man during unprotected sex, although it's less common. But this doesn’t mean that a yeast infection is considered an STI or STD (confusing, we know)! The fungus Candida, which causes yeast infections, can be transferred through sexual contact. Men who contract the fungus may develop a condition called candidal balanitis, which causes symptoms like itching, redness, and irritation of the penis. Around 15% of people with a penis who have unprotected penetrative sex with someone with a yeast infection go on to develop a penile yeast infection. To reduce the risk of transmission, it's important to avoid sexual activity while you have a yeast infection and until it has been fully treated, and always use a barrier method like condoms or dental dams.

Why does my girlfriend have a yeast infection?

Anything that disrupts the natural balance of healthy bacteria and yeast in the vagina can lead to a yeast infection. For example, antibiotic use, hormonal fluctuations, high blood sugar levels, a weak immune system, and sexual activity. When this balance gets thrown off, Candida — the fungus that causes yeast infections — can multiply too much and cause symptoms. Yeast infections are incredibly common, and up to 75% of women will have a vaginal yeast infection at least once in their lifetime. 

Why did I get a yeast infection?

There are so many reasons why you got a yeast infection (other than sheer bad luck). Sexual activity, douching, antibiotic use, high estrogen levels, a weakened immune system, and high blood sugar can all make you more prone to yeast infections. There is no single cause-and-effect reason why you develop a yeast infection, and some people are simply more susceptible to them. 

In this article, we use the terms STD and STI interchangeably — both terms mean the same thing. STD stands for "sexually transmitted disease," and STI stands for "sexually transmitted infection." While some healthcare professionals prefer to use STI because it carries less stigma, others might be more familiar with the term STD. Regardless of the word used, both refer to infections transmitted through sexual contact.