Oral thrush, also known as oral candidiasis, is when Candida, the type of fungus that causes yeast infections, overgrows in the mouth. Even though it’s easy to think of oral thrush as an infection affecting only the inside of your mouth, it can actually also affect your lips.

Candida normally lives on the skin and inside the body, in places such as the mouth, throat, gut, and vagina, without causing any problems. However, Candida can multiply and cause an infection if the environment inside the mouth or throat changes in a way that encourages fungal growth.

Anyone can have oral thrush, but people with a weakened immune system are more susceptible to the infection. A small clinical trial found that one-third of 122 patients with advanced AIDS had oral candidiasis.

Symptoms of Thrush on the Lips

Common areas affected by oral thrush include the lips, tongue, throat, roof of the mouth, and the lining of the cheeks and back of the lips, which is known as the buccal area.

Symptoms of oral thrush include the following:

  • White patches on the tongue, throat, and lipsRedness or soreness anywhere in the mouth, including the corners of the mouthCracks and tiny cuts at the corner of the mouthCotton-like feeling in the mouthLoss of tastePain with eating and swallowing

Conditions With Similar Symptoms

A few conditions can present similarly to thrush:

Thrush can also affect the esophagus—the tube that connects the throat to the stomach. Candidiasis in this area is called esophageal candidiasis or Candida esophagitis. It is one of the most common infections in people living with HIV/AIDS.

  • Leukoplakia: This is an oral condition where cells in the mouth grow excessively and appear as white patches. This condition often occurs in people who use tobacco products and can be a precursor to oral cancer. It should be evaluated by a healthcare provider, including a dentist.
  • Oral lichens planus: People with this condition have raised white lines on the tongue. It is not considered to be life threatening and may not cause any long-term complications.
  • Geographic tongue: Symptoms of this condition include a map-like pattern of reddish spots that may have a white border on the tongue. This condition is also generally considered harmless.

Since these conditions can present similarly to thrush, it’s important to see your healthcare provider if you have thrush symptoms to get an accurate diagnosis.

Causes of Lip Fungus

While yeast is inside all of us, people who have a weakened immune system are more susceptible to thrush. Different diseases that can weaken our immune system include diabetes, cancer, and HIV/AIDS.

Other risk factors that can weaken the immune system and increase someone’s likelihood of having thrush include:

  • Being less than 1 month old
  • Smoking
  • Wearing dentures
  • Using broad-spectrum antibiotics
  • Using oral or inhaled corticosteroids for conditions like asthma
  • Using long-term immunosuppressive medications
  • Taking medications that can dry out the mouth, or having chronic dry mouth
  • Frequent licking of the lips or thumb-sucking

Treatment

For mild cases of thrush, such as with infants, oral thrush often resolves on its own without any treatment. Depending on the age of the patient, as well as their baseline health status, eating lactobacillus foods, such as a yogurt, may help.

For minor to moderate thrush infections, your healthcare provider may prescribe an antifungal medication such as Bio-Statin (nystatin). This medication comes in different forms, such as lozenges, liquid, and tablets. Typically, it is applied topically to the affected areas several times a day.

For people who have a more severe case of oral thrush, an antifungal drug called fluconazole may be prescribed by your healthcare provider as a pill or even given through a vein.  

Gentian violet has also been recommended for oral thrush in the past. However, recent studies indicate that gentian violet can be toxic to the mucous membranes of the mouth and can cause ulcerations and potentially permanently stain the skin. Consult your healthcare professional before using gentian violet, to avoid potential toxicity and side effects.

A Word From Verywell

Maintaining good health is generally your best defense against oral thrush. People who have a weaker immune system, such as the very young and very old, are more likely to be affected by oral thrush.

It’s important to note, however, that people with chronic dry mouth, even if their immune system is functioning well, can also get thrush. Talk to your healthcare professional to make sure oral thrush is causing your symptoms, so treatment can begin so to alleviate your symptoms and discomfort.