Is Thrush Contagious?

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Oral thrush (oral candidiasis) and vaginal yeast infections (vaginal candidiasis) are both caused by an overgrowth of a naturally occurring fungus known as Candida albicans.

Both are characterized by the appearance of creamy white lesions that can bleed if rubbed or scraped. Given that candidiasis can involve the mouth and vagina, many people assume that the fungus can be "caught" or "passed" during oral sex. However, it isn't spread this way.

There is an association between oral sex and candidiasis, but the risk isn't linked to transmission of the fungus, it's linked to factors that promote the overgrowth of C. albicans.

Causes of Candidiasis

Candidiasis is an infection caused by overgrowth of the C. albicans fungus. The infection is considered opportunistic in that it only occurs when the usual infection controls are disrupted.

Risk factors include changes in:

  • Vaginal acidity
  • Vaginal flora
  • An immune disorder
  • Medications that suppress the immune system

This photo contains content that some people may find graphic or disturbing.

Candida albicans affecting the nails
 DermNet / CC BY-NC-ND

Although we most commonly associate candidiasis with thrush and yeast infections, it can also affect the skin, nails, esophagus, lungs, or spread through the bloodstream to affect the heart, brain, eyes, bones, and other parts of the body.

The severity of candidiasis is directly related to the severity of immune suppression. Advanced HIV infection is one of the factors that increases the risk of candidiasis becoming systemic and invasive.

This photo contains content that some people may find graphic or disturbing.

Candida albicans folliculitis
 DermNet / CC BY-NC-ND

Is Thrush Contagious?

As a naturally occurring fungus, C. albicans is not contagious. C. albicans is part of the natural flora of mucosal tissues in the mouth ad vagina. It is kept in check by a healthy immune system. As such, it is not sexually transmitted. Certain sexual behaviors may trigger the overgrowth of the fungus, leading to candidiasis.

Oral Thrush

There is no strong evidence that a vaginal yeast infection or penile yeast infection can be passed to someone performing oral sex.

A 2021 review of studies from Brazil examined the association between oral sex and the risk of oral infections. What they found was that oral candidiasis was not so much linked to sexual behaviors, but rather to an underlying disease like HIV. Infections more commonly linked to oral sex include gonorrhea, human papillomavirus (HPV), and syphilis.

People who are immunocompromised or taking certain drugs (like antibiotics or corticosteroids) that alter the body's natural flora are at increased risk of oral thrush.

The likelihood of oral thrush occurring in healthy adults is low. With that said, receiving oral sex may not be a good idea if you have a yeast infection because it may prolong the infection or trigger recurrence.

Vaginal Candidiasis

There is evidence that cunnilingus (oral-vaginal sex) can trigger vaginal candidiasis in some females. The reason for this isn't entirely clear, but it is thought that saliva introduced into the vagina can alter the concentration of lactobacillus in the vagina.

Lactobacilli are a type of lactic acid bacteria normally found in the vagina and gastrointestinal tract. It helps control C. albicans. Saliva may alter the balance of lactobacilli, thereby potentiating C. albicans overgrowth. This doesn't mean that receiving cunnilingus will cause a yeast infection, however, just that it can increase the risk.

Other risk factors include vaginal douching and frequent vaginal sex. Unprotected sex, in particular, poses a risk in that it can cause bacteria dysbiosis (an imbalance of bacteria) in the vagina up to a week after sex.

Unlike bacterial vaginosis or most sexually transmitted diseases, the risk of a yeast infection from oral sex is not inherently linked to either having multiple partners or a new sexual partner. As such, it is not considered a sexually transmitted infection.

Moreover, according to a study from the University of Michigan, the risk was in no way linked to the presence of C. albicans on any part of a male partner's body. The risk was more closely associated with cunnilingus or masturbating with saliva.

Both oral and vaginal sex may increase the abundance of lactobacillus on the penis, according to a 2019 study in the Frontiers of Medicine. But the risk of penile candidiasis is very low.

Complications

The bulk of the current evidence suggests that sexual transmission does not play a major role in vaginal or oral yeast infections. Despite this, public health organizations, including Planned Parenthood, commonly advise people with vaginal yeast infections to hold off on receiving oral sex until the infection resolves.

This is due in part to the fact that candidiasis compromises vaginal tissues, providing a greater opportunity for other infections (including bacterial and viral ones).

Moreover, the inflammation caused by Candida will trigger a steep rise in the number of immune cells, called CD4 T-cells, which are the primary target for HIV. This is evidenced by a 2003 study in the Journal of Women's Health in which females with persistent or recurrent yeast infections were more likely to seroconvert (become HIV-positive) than females who didn't have a yeast infection.

It is important to note that having recurrent or persistent yeast infections suggests an impaired immune status. So, it is not entirely clear if the yeast infection contributed to the seroconversion or if it was a sign of a weak immune system.

Prevention

Because oral sex can potentially trigger or exacerbate a vaginal yeast infection, it is important to practice safer sex if you are prone to recurrence. This includes using a dental dam when engaging in oral-vaginal sex. Dental dams can be found online and in most drugstores.

You should also consider using a water-based lubricant instead of saliva for mutual masturbation or vaginal intercourse. Some water-based lubricants like KY Jelly have no effect on vaginal lactobacilli, while others like Replens Silky Soft may promote lactobacillus growth.

If you have a yeast infection, you should either avoid sex or use condoms when engaging in vaginal intercourse. Doing so also decreases the risk of HIV.

Frequently Asked Questions

How long is thrush contagious?

Generally speaking, the fungus that commonly causes thrush (Candida albicans) is not contagious. C. albicans is normally present in the mouth, throat, and vagina without causing any problems. It typically grows and causes symptoms only when the immune system is suppressed.

How long is thrush contagious after starting medication?

Thrush is not considered contagious. While antifungal drugs can help clear a Candida infection, the drugs are not considered to be tools for prevention. In short, whether you are being treated for thrush or not being treated for thrush, your risk of infecting another person through kissing, oral sex, or other means is negligible.

Is thrush spread through sexual contact?

No. There is no evidence that oral sex can transmit Candida from one person to another. With that said, oral sex may increase the risk of a yeast infection by altering the vagina's natural flora.

A Word From Verywell

Most people do not need to be concerned about the sexual transmission of thrush or yeast infections. However, people who have recurrent vaginal yeast infections may want to discuss the benefits of safer sex with their doctor. Doing so may reduce the likelihood of candidiasis and other more potentially serious diseases.

In addition, an anti-Candida diet may reduce your risk by removing the dietary sugars that the fungus feeds on. Probiotic foods and supplements may also contribute to improved vaginal health by helping maintain the natural vaginal flora.

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