Candidiasis After Viral Illness: Causes, Symptoms, & Effective Treatment Strategies

Candidiasis is a condition caused by an overgrowth of Candida, a type of yeast naturally found in the human body. While Candida typically lives in balance with other microorganisms in the gut, mouth, and skin, disruptions to this balance can lead to overgrowth.

What Brings on Yeast Overgrowth

In the context of postviral conditions like ME/CFS and long-haul COVID, candidiasis often emerges not as a root cause but as a secondary issue. Postviral conditions frequently disrupt the delicate equilibrium of the microbiome, which can lead to immune system imbalances and gut dysbiosis—an environment where Candida can thrive. It is also suggested that preexisting candida in the gut switches from friend (commensal) to foe (pathogen) following viral infection with COVID-19 (1, 2).

Candida has long been associated with ME/CFS, not as a cause but as a consequence. Leading researcher Dr. Nancy Klimas often spoke about how surprising it was to see Candida in her ME/CFS patients. It was something she previously only encountered when working with HIV/AIDS patients, her first area of specialty. Indeed, some microbiome studies have shown increased candida in the stool of ME/CFS patients. It is therefore not surprising that candida is being talked about in those with long COVID, another post-viral condition that alters the normal immune response (3, 4). While not causative, treating candida overgrowth should be performed, where indicated, to help minimize overall symptoms.

Here are the most common factors that contribute to yeast overgrowth:

1.Overall Weakened Immune System

After a viral illness, the immune system is often left in a compromised state. This makes it harder for the body to keep Candida levels under control. Viral infections can also shift immune responses in ways that favor yeast growth, such as suppressing certain types of immune cells that typically keep Candida in check, namely neutrophils.

2. Use of Medications

Steroids, immunosuppressants, and antibiotics commonly prescribed during or after viral illnesses can create the perfect storm for Candida overgrowth. Antibiotics, in particular, can deplete beneficial bacteria, while steroids and immunosuppressants can dampen immune responses letting candida proliferate.

Testing for Candida

Testing for candida is exceptionally difficult and seldom useful. Stool testing or swab testing cannot detect systemic exposures of candida. Blood testing may not determine if candida is present now or was present in the past. The best way to test for candidiasis, if so desired, is with urine organic acids testing that looks for byproducts of Candida metabolism, such as D-arabinitol. Going with symptoms alone is usually enough to know if candidiasis is an issue for you. Let’s examine the cardinal signs and symptoms.

Cardinal Signs of Candidiasis

1. Digestive Symptoms

• Bloating and gas

• Diarrhea

• Abdominal pain or cramping

• Excessive need to clear the throat after eating

• Sugar cravings

• Itchiness around mucous membranes

2. Oral Thrush

• White patches on the tongue, cheeks, or roof of the mouth

• A cottony feeling in the mouth

• Difficulty swallowing or soreness

• Burning tongue

3. Vaginal Yeast Infections

• Intense itching and irritation

• Thick, white discharge

• Pain during intercourse or urination

4. Recurrent Infections

• Sinus infections

• Urinary tract infections (UTIs)

• Skin or nail fungal infections that recur despite treatment

These symptoms can overlap with those of postviral conditions, making candidiasis challenging to identify. If several of these symptoms are present, it may be worth exploring whether Candida overgrowth is contributing to the overall health picture.

Step 1 to Reduce Candida: A Low or No-Sugar Diet

One of the most effective steps to address Candida overgrowth is adopting a low or no-sugar diet. Candida thrives on sugar, and reducing its primary food source is critical to slowing its growth and restoring balance to the microbiome. While eliminating sugar may sound daunting, it is a foundational step for regaining control over yeast overgrowth and improving overall health.

Why Sugar Matters

Just like any other yeast, Candida uses sugar as a primary fuel source, enabling it to multiply rapidly in the gut and other parts of the body. A diet high in refined carbohydrates and sugars provides the ideal environment for Candida to thrive, exacerbating symptoms. By cutting off its food supply, you can effectively prevent the yeast from further spreading.

Foods to Avoid with Candida

To combat Candida, it’s essential to eliminate or significantly reduce foods that feed the yeast. These include:

• Refined sugars: Table sugar, candy, pastries, cookies, and other desserts

• Sweetened beverages: Sodas, fruit juices, and sweetened coffees or teas

• Refined carbohydrates: White bread, pasta, crackers, and processed snacks

• Sugary fruits: Grapes, mangoes, and other high-sugar fruits

• Alcohol: Beer, wine, and other alcoholic beverages, as they contain sugars and yeast

• Processed and packaged foods: These often contain hidden sugars, even in savory products

Using Herbs to Combat Candida

After reducing Candida’s food supply with a low or no-sugar diet, the next step is to target the overgrowth directly. Certain herbs have been shown to have antifungal properties that can help control Candida.

1. Oil of Oregano

Oil of oregano is one of the most well-researched antifungal herbs for Candida. It contains powerful compounds like carvacrol and thymol, which disrupt Candida’s cell membranes, killing the yeast. Studies suggest that oil of oregano can effectively reduce Candida populations in the gut and other areas of the body (5). Use for a limited period (e.g., two weeks on, two weeks off) to avoid gut irritation.

2. Garlic

Garlic is another powerful antifungal herb. It contains allicin, a compound that has been shown to combat Candida while also supporting the immune system. Fresh garlic or garlic supplements can help reduce Candida levels and improve gut balance (6).

3. Berberine

Berberine is a compound found in plants like goldenseal and barberry. It has broad-spectrum antimicrobial effects, making it effective against Candida while also promoting the growth of beneficial gut bacteria. Take berberine supplements as directed, often in doses of 500–1500 mg per day (7).

4. Monolaurin

Monolaurin, a medium-chain fatty acid found in coconut oil, is another excellent option for targeting Candida. It penetrates Candida’s cell walls, leading to their destruction, and is particularly effective in the gut. Read more about monolaurin here.

Saccharomyces boulardii: A Unique Ally Against Candida

Saccharomyces boulardii is a non-pathogenic yeast that acts as a probiotic. Unlike bacterial probiotics, S. boulardii is resistant to antifungal treatments, making it an excellent companion for tackling Candida. This yeast doesn’t colonize the gut long-term but works to displace harmful yeasts like Candida and support gut health during treatment.

Benefits of Saccharomyces boulardii:

• Displaces Candida: Competes directly with Candida, reducing its ability to attach to the intestinal lining.

• Reduces Inflammation: Modulates the immune response to reduce gut inflammation caused by Candida overgrowth.

• Supports Antifungal Treatments: Enhances the efficacy of antifungal herbs and medications by working alongside them.

• Protects Gut Lining: Promotes gut healing and prevents Candida from causing further damage.

Pharmaceutical Options for Treating Candida

For more severe cases of Candida overgrowth, or when the above treatments aren’t enough, pharmaceutical treatments are likely necessary. These medications target Candida directly, helping to bring the yeast back under control. Two of the most commonly used antifungal drugs are nystatin and fluconazole, each with benefits and considerations.

1. Nystatin

Nystatin is a well-known antifungal medication that works by binding to Candida’s cell walls, causing them to break down and ultimately killing the yeast. It is generally considered safe, with minimal systemic side effects since it stays within the digestive tract.

Key Features:

• Usage: Nystatin is available in oral suspension, tablet, or powder form, depending on the area being treated.

• Effectiveness: It targets Candida in the gut and oral cavity but is not absorbed into the bloodstream, making it a good choice for localized overgrowth.

• Availability: In some parts of the world, Nystatin is available over-the-counter without a prescription, making it an accessible option for managing Candida.

2. Fluconazole

Fluconazole is a systemic antifungal medication that is absorbed into the bloodstream, making it effective for more widespread Candida infections. This medication must be prescribed by your doctor if indicated.

Key Features:

• Usage: Typically prescribed in tablet form, with the dosage and duration depending on the severity of the infection.

• Mechanism: Fluconazole inhibits the synthesis of ergosterol, a critical component of fungal cell membranes, ultimately killing the yeast.

Conclusion

Candidiasis can be difficult to treat and requires ongoing maintenance treatment. This is compounded by the fact that the yeast may become resistant to the treatments over time. To avoid this, rotate between agents periodically. All of the above agents may be required for the most stubborn candidiasis overgrowth. Others may find that 1 or 2 treatment approaches will be effective. Monitor your symptoms carefully to fully understand your unique situation. Since postviral conditions are chronic and lifelong, some degree of lifelong maintenance of candidiasis is likely required.

Another major issue for sensitive individuals is the die-off or Herxheimer reaction. This is likely to occur with any treatment for candidiasis but should subside in time. It may be unpleasant but it’s a sign that things are working! Be prepared for worsened symptoms when starting a candida protocol. Be patient. Go slow. Restoring gut balance takes time; stick to your protocol for several weeks to months to see lasting improvements.

References

1 Bistagnino F, Pizzi D, Mantovani F, Antonino JR, Tovani-Palone MR. Long COVID and gut candidiasis: What is the existing relationship?. World J Gastroenterol. 2024;30(37):4104-4114. doi:10.3748/wjg.v30.i37.4104

2 Lagree K, Chen P. Candida makes a lasting impression in COVID-19. Nat Immunol. 2023;24(11):1782-1784. doi:10.1038/s41590-023-01648-1

3 Cater RE 2nd. Chronic intestinal candidiasis as a possible etiological factor in the chronic fatigue syndrome. Med Hypotheses. 1995;44(6):507-515. doi:10.1016/0306-9877(95)90515-4

4 Evengård B, Gräns H, Wahlund E, Nord CE. Increased number of Candida albicans in the faecal microflora of chronic fatigue syndrome patients during the acute phase of illness. Scand J Gastroenterol. 2007;42(12):1514-1515. doi:10.1080/00365520701580397

5 Soltani S, Shakeri A, Iranshahi M, Boozari M. A Review of the Phytochemistry and Antimicrobial Properties of Origanum vulgare L. and Subspecies. Iran J Pharm Res. 2021;20(2):268-285. doi:10.22037/ijpr.2020.113874.14539

6 Marchese, A., et al. (2016). Antifungal and antibacterial activities of allicin: A review. Trends in Food Science & Technology, 52, 49–56.

7 Picheta N, Piekarz J, Burdan O, Satora M, Tarkowski R, Kułak K. Phytotherapy of Vulvovaginal Candidiasis: A Narrative Review. Int J Mol Sci. 2024;25(7):3796. Published 2024 Mar 28. doi:10.3390/ijms25073796