Is Thrush Contagious?

By Sarah Malka, MD
Medically reviewed
September 21, 2021

When you think of a yeast infection, what probably comes to mind is a vaginal yeast infection—but while these are common, yeast infections can also happen in other parts of the body, such as your esophagus, skin, or mouth.

All of these infections are uncomfortable, common infections caused by the overgrowth of a fungus called candida. And when that infection is in your mouth, it’s called oral thrush.

In this article, I’ll review the causes, symptoms and treatment for oral thrush.

I’ll also discuss if these infections are contagious, and how to prevent them.

What Causes Thrush? 

Candida albicans is a naturally occurring fungus that lives in your body and mouth.

Normally, your body is able to maintain a balance of candida fungus in your body, but sometimes this fails.

The fungus then overgrows, and a candida infection can occur.

When this happens within your mouth, it can cause thrush. Thrush is most common in infants and those with a compromised immune system.

Some common causes and risk factors for oral thrush (oropharyngeal candidiasis) infection include:

  • Medications like antibiotics, birth control, and corticosteroid inhalers that disrupt your natural balance of microorganisms
  • Dentures
  • Chronic dry mouth
  • Smoking 
  • Weakened immune system resulting from medications or health conditions, such as drugs to treat cancer or an organ transplant
  • Uncontrolled diabetes, which can cause saliva that may contain large amounts of sugar, which can encourage candida growth
  • HIV/AIDS
  • Infants, who often have milk in their mouth, which can lead to candida overgrowth

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Is Thrush Contagious?

Oral Thrush

Oral thrush is not considered contagious, but it can be passed back and forth between at-risk individuals or from mother to infant while breastfeeding.

In otherwise healthy people, it is very unusual for thrush to be passed by kissing or other close contact.

This is because candida is already present in everyone’s mouth–it only becomes thrush when it overgrows.

Women who are breastfeeding may have normal amounts of candida on their breasts and nipples, which can be transferred to their baby while breastfeeding.

While growth of candida on the breasts and nipples does not always result in an infection, this extra yeast in a baby’s mouth—as well as the sugary milk there—can increase their risk of thrush.

When a baby has thrush, that does not mean the mother will necessarily develop an infection. Infants may experience a yeast diaper rash at the same time as oral thrush.

Reach out to your pediatrician or healthcare professional if your infant exhibits signs of oral thrush such as mouth pain or a thick white coating to the tongue.

A candida diaper rash can typically be easily treated with over-the-counter clotrimazole (Lotrimin AF) cream. 

Vaginal Candidiasis

Vaginal yeast infections can be passed to sexual partners are thrush, or another type of infection.

Thrush can be contracted through oral sex with a partner experiencing a vaginal or penile yeast infection.

Though very uncommon, vaginal candidiasis is contagious through sex.

An estimated 15% of men experience symptoms of a penile yeast infection after sexual intercourse with an infected partner.

Men who have not been circumcised and men with diabetes are at higher risks of such infections.

If both partners have vaginas, it’s possible that yeast infections might be passed from one partner to the other.

Seek treatment if you think you might have a yeast infection.

Symptoms of Thrush

Symptoms of oral thrush can come on suddenly.

Common symptoms include creamy, white lesions on your tough, inner cheeks, the roof of your mouth, gums and tonsils.

You also might experience redness or soreness inside the corners of the mouth, a cottony feeling in your mouth loss of taste, or raised white lesions in your mouth that look like cottage cheese.

When scraped at, the lesions/white patches may stick to the tongue or bleed. 

Diagnosis and Treatment

Oral thrush is diagnosed based on symptoms and examination of the lesions.

A provider might also take a swab or scraping of the lesion for further examination, but this is typically not necessary.

Candidiasis in the mouth is treated using prescription oral antifungal medications, such as clotrimazole, miconazole, or nystatin.

The type of antifungal medication, the dosage, and the length of treatment are determined based on age and the severity of the infection. 

Complications

While most yeast infections are not serious, some individuals with weakened immune systems or preexisting medical conditions may experience more severe infections.

Oral thrush can spread to the esophagus, resulting in painful swallowing.

In very severe cases, thrush can travel to other parts of the body, infecting the lungs, liver and skin. 

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Prevention 

There are a number of ways individuals can prevent an oral thrush infection.

  • Good oral hygeine: Brush your teeth and floss daily as directed by your dentist.
  • Regular dental visits: See the dentist regularly for check-ups and oral maintenance.
  • Rinse your mouth: After meals, especially those high in sugar, rinse your mouth with water or mouthwash.
  • Eat foods with healthy probiotics: Try introducing healthy probiotic-containing foods, like yogurt, to maintain good bacteria—bacterial balance can prevent overgrowth of candida throughout your body.
  • Don’t smoke or vape.
  • Balance your blood sugar: If you have diabetes, work with your healthcare provider to balance blood sugar levels.

Frequently Asked Questions

How long is thrush contagious?
Thrush is not technically contagious, but is transmittable, especially to high-risk individuals. Since candida lives on the skin and in the mouth naturally, there is no specific length of time of contagion. But if you have an active overgrowth or infection, it can be more likely that you will pass it to others who are at risk while you have symptoms.
Is thrush contagious through kissing?
While very rare, thrush can be transmitted through kissing, especially to immunocompromised or high-risk individuals. If you exchange saliva through kissing with someone you suspect has thrush, that does not necessarily mean you will become infected. Most people with a normal immune system do not “catch” oral thrush from someone else.
How long is thrush contagious after starting medication?
With treatment, oral thrush symptoms may go away within a matter of days, and will usually clear up completely within a few weeks of medication. Longer treatment may be needed for severe infections or individuals with compromised immune symptoms.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sarah Malka, MD

Dr. Sarah Malka is a board certified emergency medicine physician with K Health. She completed her residency at Harvard Medical School.