Does Baking Soda Kill Fungus? The Science Explained

Baking soda does have genuine antifungal properties, and there is solid laboratory evidence behind that claim. In one of the most cited studies on the topic, a concentration of just 10 grams per liter of sodium bicarbonate inhibited the growth of roughly 80% of fungal isolates responsible for common skin and nail infections. But the story is more nuanced than a simple yes, because not all fungi respond equally, the concentration matters enormously, and what works in a petri dish does not always translate to a reliable treatment on your body or in your garden.

What Laboratory Testing Actually Shows

The clearest picture of baking soda’s antifungal power comes from studies that tested it directly against fungi in controlled lab conditions. A study published in Mycopathologia tested sodium bicarbonate against a range of fungal species responsible for superficial human infections, including yeasts like Candida, dermatophytes that cause athlete’s foot and ringworm, and environmental molds. When clinical specimens from infected nails and skin scrapings were grown on media supplemented with 10 grams per liter of baking soda, fungal growth was completely stopped in about four out of five specimens and reduced in most of the rest.¹ That is a striking result for something sitting in most kitchen cupboards.

Agricultural research tells a similar story. Sodium bicarbonate reduced the growth of Geotrichum candidum, a fungus that causes sour rot in carrots, by over 90% in lab tests.² Against Botrytis cinerea, the gray mold that ruins grapes and strawberries, it completely stopped growth at concentrations as low as 0.25%.³ So yes, the antifungal activity is real and reproducible across multiple fungal species. The question is really about how strong the effect is, and whether it is strong enough to matter in practice.

How Baking Soda Disrupts Fungi at the Cellular Level

The mechanism by which baking soda harms fungi is not fully understood, and researchers have noted this gap openly. A dermatology review pointed out that the exact mode of action remains unexplored despite the consistent antifungal results.⁴ That said, research on Aspergillus niger has offered some clues. When researchers examined what baking soda does to this mold at a cellular level, they found it disrupts the structural integrity of both the cell membrane and the membranes surrounding mitochondria. It also decreased the activity of enzymes involved in the cell’s energy production cycle, lowered the electrical potential across mitochondrial membranes, reduced ATP output, and cut the amount of ergosterol in the cell’s outer membrane.⁵

Ergosterol is worth pausing on for a moment. It is a critical component of fungal cell membranes, and many prescription antifungal drugs work by targeting it or its production. The fact that baking soda appears to reduce ergosterol content suggests it may be attacking one of the same vulnerabilities that pharmaceutical antifungals exploit, though through a different and likely less precise pathway. There is also a simpler theory: baking soda raises the pH of its environment, and most pathogenic fungi prefer slightly acidic conditions. Shifting the pH toward alkaline territory makes the environment less hospitable, even before any direct membrane damage kicks in.

Not All Fungi Are Equally Vulnerable

One of the most practically important findings from the lab research is that different categories of fungi need very different concentrations of baking soda to be inhibited. The Mycopathologia study measured the concentration needed to stop 90% of tested organisms and found a clear hierarchy. Yeasts were the most sensitive, needing only about 5 grams per liter. Dermatophytes required four times that, at 20 grams per liter. Molds were the toughest to kill, needing 40 grams per liter.¹

This hierarchy matters because the fungal infections people encounter in daily life fall across those categories. Oral thrush and vaginal yeast infections are caused by Candida species, which are yeasts and therefore the most susceptible. Athlete’s foot, jock itch, and ringworm are caused by dermatophytes, which need a much stronger concentration. Black mold in your bathroom is a true mold and sits at the far end of the resistance spectrum. So when someone says “baking soda kills fungus,” the honest follow-up question is always “which fungus?”

Skin and Nail Infections

For the many people who find this topic through a search about foot fungus or toenail infections, the evidence is genuinely promising but comes with a significant caveat: almost all of it is from lab and ex vivo testing, not from clinical trials where people applied baking soda to their bodies and had outcomes measured against a placebo.

The strongest evidence comes from the study that tested baking soda against infected nail clippings and skin scrapings outside the body. At a concentration of 10 grams per liter, it fully inhibited fungal growth in 79% of those clinical specimens after seven days and reduced growth in another 17%.⁴ Those numbers are encouraging, but growing fungi on a nail clipping in a lab dish is a far simpler challenge than treating a fungal infection embedded in a living toenail. In a nail clipping, the baking soda has direct access to the fungus. In a real toenail, the infection hides beneath layers of hard keratin, and any topical agent has to penetrate that barrier while remaining at an effective concentration.

There is also the pH question. Healthy skin maintains a slightly acidic surface pH, and that acid mantle serves as a defense against infection. Routinely applying baking soda to your skin shifts the surface toward alkaline, which may discourage some fungi but could also compromise that natural barrier. For brief, targeted application, like soaking a foot in a baking soda bath, this is unlikely to cause problems. For daily use across large skin areas, the trade-off is less clear. If you are dealing with a stubborn or spreading fungal infection, prescription antifungals remain the evidence-based first line, while baking soda occupies a reasonable supporting role.

Agricultural and Food Preservation Uses

Baking soda has a much longer track record in agriculture and food preservation than in human medicine, and some of the most practical results come from this arena. Postharvest treatment of citrus fruit provides a useful case study. Blue mold and green mold, caused by Penicillium species, are the bane of orange growers and packinghouses. Researchers found that dipping oranges in a sodium bicarbonate solution at 2 to 4% reduced blue mold by more than half. In one set of experiments, baking soda treatment at room temperature drove blue mold incidence down to about 6% and green mold to about 6%, compared with near-total infection in untreated controls.⁶ The 1% concentration, however, was ineffective, reinforcing the principle that concentration is everything.

Against gray mold on table grapes, baking soda at just 0.25% completely inhibited growth of Botrytis cinerea in vitro, and salt solutions at 1% significantly reduced mold incidence on inoculated grapes stored at room temperature for a week.³ These food-safety applications are appealing partly because baking soda is nontoxic and leaves no harmful residues on food, unlike synthetic fungicides.

In soybean production, sodium bicarbonate has also shown promise against seed-borne pathogens. Researchers testing it alongside papaya leaf extracts found that it could inhibit Aspergillus niger growth at concentrations comparable to the plant extract, suggesting its potential as a low-cost seed treatment in resource-limited settings.⁷

Why Baking Soda Works Better in Combination

One of the clearest themes across the research is that baking soda performs significantly better when paired with another agent than when used alone. This shows up in nearly every context, from medicine to farming.

In a study on Candida glabrata, a yeast that commonly causes drug-resistant infections, combining baking soda with fluconazole (one of the most widely prescribed antifungal drugs) produced a synergistic effect. The combination achieved fungicidal activity that neither agent matched on its own, meaning it actually killed the yeast cells rather than merely slowing their growth.⁸ This is particularly interesting because C. glabrata is increasingly resistant to fluconazole alone, and anything that restores the drug’s effectiveness without requiring higher doses is clinically valuable.

The pattern repeats in agriculture. When sodium bicarbonate was applied alone at 2 grams per liter to cucumber plants to protect against powdery mildew, it failed completely. But when combined with a horticultural spray oil, its fungicidal activity was enhanced enough to protect less-resistant cultivars.⁹ Similarly, commercial citrus fungicides like fludioxonil and thiabendazole had markedly increased activity when sodium bicarbonate was added to the treatment, even at low fungicide concentrations.¹⁰ Against Aspergillus niger, combining baking soda with natamycin (a natural antifungal) at much lower individual doses achieved the same total inhibition as using either agent at a much higher dose alone.⁵

The practical takeaway here is that baking soda is best understood as a booster rather than a standalone antifungal. It weakens the fungus through the mechanisms described earlier, making it more vulnerable to whatever other antifungal agent is present. Used alone at moderate concentrations, it is often too weak to finish the job.

Where Baking Soda Falls Short

The research makes it easy to get overenthusiastic, so it is worth being clear about where baking soda does not deliver. Against citrus green mold caused by Penicillium digitatum, baking soda alone showed weak activity in a study that compared it to several other salt treatments. While it could inhibit spore germination, its effective dose was considerably higher than that of sodium carbonate (washing soda) or potassium carbonate.¹¹ Against cucumber powdery mildew, as mentioned, it outright failed as a protectant at low concentration without an additive.⁹

There is also the matter of contact time. In lab studies, fungi are exposed to the baking soda solution continuously for hours or days. In real life, if you are sprinkling baking soda on a shower wall or soaking your feet for 15 minutes, the exposure time is dramatically shorter and the concentration at the site of infection is harder to control. Molds growing in damp environments also have a continuous moisture supply that may dilute or wash away the baking soda, and they have a physical structure (hyphae extending into porous materials like grout and wood) that a surface application may not reach.

For toenail fungus specifically, the nail itself is the main obstacle. Nail plate is dense and relatively impermeable, which is the same reason prescription topical antifungals struggle with this infection and why oral medications are often needed. If pharmaceutical formulations specifically engineered to penetrate the nail have limited success, a baking soda paste sitting on the surface faces even steeper odds.

Baking Soda Versus Washing Soda

A common point of confusion is the difference between baking soda (sodium bicarbonate, NaHCO₃) and washing soda (sodium carbonate, Na₂CO₃). They are related chemicals but not interchangeable. Washing soda is more alkaline and generally more potent as an antifungal. In the citrus mold study, sodium carbonate required a much lower concentration than sodium bicarbonate to inhibit spore germination.¹¹ When treating oranges for blue mold, sodium carbonate at 45 degrees Celsius reduced incidence to 14%, while baking soda at room temperature achieved an even lower 6%, though the temperature difference makes a direct comparison tricky.⁶

Washing soda’s higher alkalinity also makes it harsher on skin and plant tissues, which is why baking soda tends to be the preferred choice for applications where safety and gentleness matter. For cleaning hard surfaces like tile and grout where mold has established itself, washing soda may be more effective, but you should wear gloves and keep it away from plants. For anything involving food or skin, baking soda is the safer option despite being somewhat less potent.

Using Baking Soda Around the House

One small study tested a homemade cleaning mixture of baking soda, dish soap, and white vinegar against commercial products (Lysol and Clorox) for preventing mold growth on preservative-free white bread. The homemade mixture actually showed the lowest microbial growth out of all treatments over a 12-day observation period, outperforming both commercial products.¹² This was a small experiment and should not be overinterpreted, but it does suggest that for basic household mold prevention, a baking soda solution can hold its own against commercial sprays.

For practical household use against mold, a paste of baking soda and water applied to grout, caulk, or tile and left for 10 to 15 minutes before scrubbing is a common approach. The physical scrubbing removes the mold colony while the baking soda raises the local pH to discourage regrowth. It will not penetrate porous materials as well as a bleach solution, and it will not kill deeply embedded mold in drywall or wood. For surface mold on hard, nonporous surfaces in bathrooms and kitchens, it is a reasonable and nontoxic first step. If the mold keeps coming back, the underlying moisture problem needs to be addressed, because no surface treatment, baking soda or otherwise, will permanently solve a mold issue driven by chronic dampness.

One thing to avoid: mixing baking soda with vinegar in the same solution and expecting enhanced antifungal power. The acid-base reaction between them is visually satisfying (all those bubbles) but chemically self-defeating. The two neutralize each other, producing mostly water and carbon dioxide gas, and the resulting solution has less antifungal activity than either ingredient used separately. If you want to use both, apply them in sequence rather than together.

1
PubMed. Antifungal activity of sodium bicarbonate against fungal agents causing superficial infections
2
Journal of Phytopathology. Effect of various salts on the growth and development of Geotrichum candidum, the causal agent of carrot sour rot
3
Postharvest Biology and Technology. Salt strategies to control Botrytis mold of ‘Benitaka’ table grapes and to maintain fruit quality during storage
4
Journal of Integrative Dermatology. Baking Soda and the Skin: A Review of Baking Soda in Dermatology
5
PubMed Central. Isolation, identification, biological characteristics, and antifungal efficacy of sodium bicarbonate combined with natamycin on Aspergillus niger from Shengzhou nane (Prunus salicina var. taoxingli) fruit
6
PubMed. Control of Postharvest Blue and Green Molds of Oranges by Hot Water, Sodium Carbonate, and Sodium Bicarbonate
7
International Journal of Biological and Chemical Sciences. Antifungal activities of Carica papaya and sodium bicarbonate against Soybean fungi
8
Brazilian Journal of Pharmaceutical Sciences. Synergistic interaction of fluconazole/sodium bicarbonate on the inhibition of Candida glabrata phospholipase gene
9
Massey University. The mode of action of sodium bicarbonate / additive mixtures against cucumber powdery mildew disease
10
PubMed. Residue levels and efficacy of fludioxonil and thiabendazole in controlling postharvest green mold decay in citrus fruit when applied in combination with sodium bicarbonate
11
PubMed. Control of Citrus Green Mold by Carbonate and Bicarbonate Salts and the Influence of Commercial Postharvest Practices on Their Efficacy
12
Expedition. Effectiveness of Commercial and Homemade Cleaning Products on Preventing White Bread Microbial Growth