• Oral thrush is a fungal infection of the oral mucosa caused by Candida species. It is the most common human fungal infection.
  • Oral thrush may refer to candidiasis in the mouths of babies, or if occurring in the mouth or throat of adults it may also be termed candidosismoniliasis, or pseudomembranous candidiasis
  • Topical candidiasis is not normally a dangerous condition except in the rare cases when it enters the bloodstream of people with weakened immune systems.
  • Candida is a normal component of oral flora in 25-75% of healthy, immunocompetent people. Decrease in competitive bacteria population caused by broad spectrum antibiotic use may increase growth of Candida.
  • Candida may also occur in people who are treated with inhaled corticosteroids for asthma or rhinitis; in people who wear dentures; and in people with suppressed immune systems (disease or drug) or certain health conditions (e.g. diabetes).
  • Thrush occurs in 2-5% of healthy newborns, as it is acquired from their mothers at birth. 
  • Thrush is uncommon in healthy older children (>1 year of age), teenagers and adults in the absence of a predisposing factor such as recent antibiotic use, immunosuppression or inhaled corticosteroid use. If experiencing thrush, these patients should be refered to their primary care provider for further evaluation to check for underlying medical conditons or other causes. 
  • Risk factors:
    • Medical conditions:
      • Immunocompromised
      • Malignancy
      • Sjögren's syndrome 
      • Diabetes
      • Cushings disease
    • Medications:
      • Corticosteroids including inhaled corticosteroids (incorrect technique, not rinsing mouth post-use)
      • Recent broad-spectrum antibiotic use
      • Chemotherapy or radiation therapy
    • Extremes of age (Newborn, >65)
    • Pregnancy
    • Dentures
    • Poor oral hygiene
    • Chronic dry mouth
    • Smoking 
  • For photos and more information go to :
    DermNet NZ

There are several variants of oral candidiasis, however, acute pseudomembranous candidiasis is the most common form.  

Symptoms of acute pseudomembranous candidiasis (aka thrush):

  • Superficial, white to creamy-white plaques or patches on buccal mucosa, tongue, lips, and/or palate, which can be scraped off to reveal an erythematous base and cause mild bleeding.
  • May be "milk curd" or "cottage cheese" like
  • Most often asymptomatic, but can cause mild pain
  • Infants may be fussy and refuse to eat
  • May cause a "cottony" feeling in the mouth and loss of taste.
  • Concurrent candidal diaper dermatitis possible [see Diaper Dermatitis Guidelines ]

Oral thrush is diagnosed based on signs, symptoms and history. Rule out the following conditions that may present with similar signs/symptoms:

  • Atrophic candidiasis (erythematous candidiasis) - erythematous lesions can be found on the palate and on the tongue and may occur as acute or chronic types. 
    • Acute - occurring as plaques are shed, exposing the underlying erythematous lesions following pseudomembranous candidiasis. 
    • Chronic - often occurring in the elderly, patients with HIV, or in denture wearers (sometimes referred to as denture stomatitis). 
      • In denture wearers, the lesions are often chronic, red & edematous and appear on the mucosa that comes in contact with the denture.  Although usually symptomless, sometimes results in mild soreness, burning or tingling beneath the denture. Refer to dentist or denturist.
  • Angular cheilitis - erythematous fissuring at the angles of the mouth due to a mixed bacterial-fungal infection; commonly associated with denture stomatitis. May also be a sign of B12, folic acid or iron deficiency.
  • Periodontal infection - red swollen or bleeding gums, foul breath, & absence of white spots. A key differentiating factor is that a periodontal infection will have significant swelling, but oral thrush will not. Refer to dentist or patient's primary care provider for counselling and/or prescription mouthwash (e.g. chlorhexidine 0.12 % oral rinse).

  • Burns will cause significant redness and swelling in the mouth, which should not be seen with oral thrush. Common in bottle-fed infants.

  • Leukoplakia causes chronic lesions seen mostly in smokers and males over 30.  These are small, translucent white plaques, usually on the tongue.  The plaques cannot be wiped off as easily as oral thrush.  These lesions can be cancerous, so a biopsy is recommended if this condition is suspected.

  • Aphthous ulcers are one or more shallow, usually painful sores with a white coating.  They appear as discrete lesions, which helps differentiate it from oral thrush.

  • Herpes simplex infection is indicated by multiple ulcerous or vesicular lesions. Primary herpes (first episode) may also be associated with fever, swollen glands, poor appetite.
  • Coxsackievirus (hand, foot and mouth disease) usually occurs in children, manifests as small (1-2 mm), tender lesions usually on the posterior pharynx including tonsils, soft palate, uvula and raised areas on hands and feet. No need to refer, but recommend fluids to prevent dehydration.

  • Lichen planus  appears as inflammatory, scaly, white or striated patches possibly caused by local trauma to tissue.

  • Adverse drug reaction - sore mouth with diffuse redness and/or bullae/blisters on oral mucosa occurring after initiation of a new medication. Stevens Johnson Syndrome / Toxic Epidermal Necrolysis (rare) can occur from a few days up to 2 months after starting a medication.  Lips may be crusted & patient may have mouth ulcers. 

Patients with signs/symptoms typical of oral thrush often do not require further investigation, however an assessment by the patient's primary care provider should be recommended in the following situations:

  • Patients >1 yr old & <65 years old without a predisposing factor such as recent antibiotic use (within last 2 weeks), immunosuppression or inhaled corticosteroid use. If experiencing thrush, these patients should be refered to their primary care provider for further evaluation to check for underlying medical conditons or other causes. 
  • Patient is on chemotherapy or immunocompromised due to drug therapy or medical conditions.

  • Patient wears dentures infection will be limited to the mucosa that comes into contact with the denture. Requires optimal denture care as well as referral. 
  • Other organ involvement such as conjunctivitis, uveitis or accompanying genital ulcers.

  • Any lesion present for 3 weeks or longer should be referred to patient's primary care provider as it may require biopsy and/or systemic antifungal treatment.

  • Possible adverse drug reaction.  If a prescription medication is suspected, refer to patient's primary care provider for evaluation and possible change in medication.

  • Suspect primary viral herpes infection (primary herpes gingivostomatitis) - multiple crops of ulcerous or vesicular lesions on the tongue, palate, gingiva, buccal mucosa and lips. Often accompanied by fever, chills, muscle aches and malaise. Refer to patient's primary care provider for evaluation.

  • Recent burn to the mouth.

  • Unable to confirm diagnosis of oral thrush. Refer for further evaluation and/or supervised therapy.

1. Non-pharmacological treatment:

  • Although thrush can be transmitted during breastfeeding, the incidence of this condition appears to be greater in infants who are formula-fed. For this reason, proper storage of formula is important. 
  • Ensure pacifiers & bottle nipples are sterilized by boiling after each use.
  • Mothers of breastfed infants should use nursing pads to stop transfer of organism to clothing. These should be washed frequently or disposable nursing pads can be used, but must be changed after each feeding. Disposable pads with plastic or occlusive liners may increase the risk of yeast infection as they promote dampness.
  • If the baby is breastfed, ask about symptoms of maternal colonization such as:
      • nipple pain, burning, and/or itching
      • cracked, red, shiny skin on nipple & areola
    • It is important that both the mother and the baby are treated. The mother may use a topical antifungal such as clotrimazole or miconazole. The breast area should be wiped off before nursing the baby & the cream reapplied after feeding. 
  • If the patient wears dentures (patient must be referred), optimal denture care must be done:
    • Remove dentures overnight
    • Wear for maximum of 6 hours per day during infection
    • Clean daily and soak in disinfectant overnight in proper disinfecting solution, depending on denture type
    • Clean gums, tongue and affected areas with soft toothbrush
    • Ensure proper fit
  • Toothbrushes should be replaced often until infection clears up.
  • Rinse mouth after using steroid inhalers or nasal sprays. Use of aerochambers with oral inhalers can also help to prevent infection. 
  • To soothe irritated mouth, dissolve 1/2 teaspoon salt in 1 cup of warm water. Swish and then spit it out, don't swallow.
  • Do not use OTC mouthwashes that contain alcohol as they may cause the mouth to become dry.
  • Keep the mouth moist by taking frequent sips of water or sucking on ice chips or sugar-free lozenges. 

2. Prescription Drug Option:
  • Nystatin Suspension 100,000 units/ml
    • Treatment option for mild disease (level 2 [mid-level] evidence)
  • Dosage:
    • Children and adults: Swish and swallow 4 to 6 ml orally 4 times daily for 7-14 days (minimum of 2 days after symptoms resolve). Provide a 7 days supply & 1 refill.

    • Infants (≤12 months): Use 1 or 2 ml 4 times daily for 7-14 days (minimum of 2 days after symptoms resolve). Apply 1/2 the dose to each side of the mouth.  May use cotton swab or finger to apply inside the infant's cheeks and on tongue.    
  • Pregnancy: Safe for use during all trimesters.

  • Lactation: Compatible with breastfeeding. Poorly absorbed orally and does not enter breast milk.

Directions for use:

  • Adults and children: Swish, retain in mouth for as long as possible, up to a few minutes and swallow. Repeat this procedure 4 times daily.  
  • Infants: Give 100,000 units (1ml) to 200,000 units (2ml). Place 1/2 the dose in each side of mouth 4 times a day. Apply with a cotton swab or use a clean finger to sweep solution inside infant's cheeks and on tongue.
  • Caution should be used when given to infants to avoid choking.
  • Monitor infants closely for decreased oral intake which can result in a nutritional deficiency.
  • Advise to continue treating for at least 2 days after symptoms resolve to ensure successful outcome.

Assess Benefit

  • Follow up in 7 days
  • Onset of action: Symptomatic relief in 48 - 72 hours.
  • If significant improvement, but not full resolution, provide another 7 day supply & recommend using for 2 days after symptoms have resolved. 
  • Refer to patient's primary care provider if unsuccessful after 14 days of treatment.

Adverse Effects:

  • Usually well tolerated.
  • Usually doesn't interact with other medications, as not largely absorbed from GI tract.
  • Discontinue therapy if irritation or sensitization (rash, urticaria, contact dermatitis) occurs and refer to patient's primary care provider.

Detailed information on contraindications, cautions, adverse effects and interactions is available in individual drug monographs in the CPS (e-CPS), Lexi-Comp, AHFS, www.drugs.com or other reliable drug monograph references. For comprehensive drug comparisons, see RxFiles charts (www.rxfiles.ca). This information should be routinely consulted before prescribing.

Generic Name

Nystatin Oral Suspension

100,000 U/ML


  • pseudoDIN: 00951093
    • Max of 4 claims per 365 days per patient

  • May prescribe sufficient quantity to treat ONE episode of thrush, which is usually 7 days with a refill
    • If patient has had significant healing, but not full resolution after 7 days, may extend treatment to 14 days.  
    • Dispense enough medication for a 1 week supply based on daily dose & provide 1 refill
    • Each new episode of thrush is to be treated as a distinct episode and re-assessed.

  • Only products with an official indication from Health Canada for thrush are considered for these guidelines. Only the active ingredients in the "products" section are approved for pharmacist prescribing.
  • MedBroadcast Clinical Team. Oral thrush. C-Health.. http://chealth.canoe.com/condition_info_details.asp?channel_id=0&relation_id=0&disease_id=313&page_no=1.
  • Quail G. The painful mouth. Aust Fam Physician. 2008;37(11): 935-8. http://www.racgp.org.au/afp/200811/28197. Published November 2008.
  • Pappas PG, Kauffman CA, Andes D, et al. Clinical practice guidelines for the management of candidiasis: 2009 update by the infectious diseases society of America. Clin Infect Dis. 2009;48:503-35. doi:10.1086/599376.
  • Mayo Clinic Staff. Oral thrush. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/oral-thrush/basics/definition/con-20022381. Updated August 12, 2014.
  • DynaMed. Oral candidiasis in children an adults. EBSCO Publishing. http://www.ebscohost.com/dynamed. Subscription required. Updated September 26, 2013.
  • Weisse ME. Candida. In: Kliegman RM, ed. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, PA: Elsevier Inc; 2007.
  • Pammi M. Clinical manifestation and diagnosis of Candida infection in neonates. UpToDate. http://www.uptodate.com. Subscription required. Updated September 8, 2015.
  • Sung DH. Oral Candidiasis. In: Repchinsky C, ed. Patient Self-Care. 2nd ed. Ottawa, ON: Canadian Pharmacists Association; 2010: 904-909.
  • Wlock K. Oral Candidiasis. In: Jovaisas B, ed. Compendium of Therapeutics for Minor Ailments. Ottawa, ON: Canadian Pharmacists Association; 2014: Available at https://www.e-therpeutics.ca. Subscription required.

No part of this work may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the copyright holder. For copyright permission requests, please contact druginfo@usask.ca.

Prepared by medSask
Reviewed by Dr. P Fourie, Family Physician; Dr. Yvonne Shevchuk, Professor, College of Pharmacy & Nutrition;
Dr. Brenda Schuster, PharmD
Funded by the Saskatchewan College of Pharmacy Professionals
Posted May 2010. Updated May 2017