Soaking your feet in a baking soda bath primarily works as an antifungal treatment, an odor neutralizer, and a mild itch reliever. The evidence behind each of these uses varies, and the story is more nuanced than most home-remedy lists suggest. Baking soda is alkaline, which creates conditions that many skin fungi struggle to survive in, but that same alkalinity can work against your skin’s natural defenses if overused.
How It Fights Foot Fungus
The strongest evidence for soaking feet in baking soda involves its antifungal activity. A study testing sodium bicarbonate against 70 fungal strains taken from human skin and nail samples found that a solution of just 10 grams per liter inhibited growth of roughly 80% of the isolated fungi. The fungi tested included the exact species responsible for athlete’s foot and toenail infections: dermatophytes like T. rubrum and T. interdigitale, along with common yeasts and molds. The effective concentration varied by fungal type, with yeasts being the most sensitive and molds requiring a stronger solution.1Journal of Integrative Dermatology. Baking Soda and the Skin: A Review of Baking Soda in Dermatology
The same research went further with an ex vivo phase, testing baking soda against fungal strains scraped directly from infected human toenails and foot skin. When the growth medium was supplemented with baking soda, fungal growth was fully inhibited in about 79% of those specimens after seven days, and reduced in another 17%. Only one specimen out of 24 grew normally despite the baking soda.1Journal of Integrative Dermatology. Baking Soda and the Skin: A Review of Baking Soda in Dermatology
This is genuinely promising, but it comes with a caveat that matters: these results were obtained in controlled laboratory and ex vivo conditions, not in a clinical trial where people soaked their feet and had outcomes tracked over weeks. A foot soak delivers a lower and less consistent concentration of baking soda to the affected tissue than a lab dish does, especially when the fungus has burrowed under a toenail. Researchers have confirmed baking soda’s antifungal activity against the most common agents of superficial fungal infections, but the leap from “kills fungi in a dish” to “cures your athlete’s foot” involves variables that lab studies don’t capture.2PubMed. Antifungal activity of sodium bicarbonate against fungal agents causing superficial infections
Why Toenail Fungus Is a Harder Problem
If you have athlete’s foot between your toes, the fungus lives on superficial skin that a soak can actually reach. Toenail fungus is a different story. The nail plate acts as a physical barrier, and the fungus colonizes the nail bed underneath. Soaking the foot in baking soda water exposes the nail surface to the solution, but penetrating the full thickness of a thickened, infected nail is something that even prescription antifungal creams struggle with. Oral antifungal medications work for nail fungus partly because they reach the infection from the inside, through the bloodstream, bypassing that barrier entirely.
That doesn’t mean a baking soda soak is useless for fungal nails. It may help control fungal spread on surrounding skin and keep the environment less hospitable to reinfection. But expecting a soak alone to clear a well-established toenail infection is unrealistic. If your nails are discolored, thickened, or crumbling, a soak might be a useful complement to medical treatment rather than a substitute for it.
Reducing Foot Odor
Foot odor is mostly caused by bacteria breaking down sweat into volatile fatty acids. Baking soda addresses this from two angles. First, it neutralizes acidic odor compounds directly, which is the same reason people keep an open box in the fridge. Second, its mild antibacterial and antifungal properties can reduce the microbial load doing the fermenting in the first place.
An experimental study designed to test baking soda’s odor-reducing ability used putrefied amniotic membrane as an odor source and found statistically significant odor reduction with sodium bicarbonate, both on its own and in combination with activated charcoal.3Bioline International / Indian Journal of Dermatology, Venereology and Leprology. Activated charcoal and baking soda to reduce odor associated with extensive blistering disorders That study was aimed at wound odor rather than feet specifically, but the chemistry is the same: baking soda is effective at reducing the intensity of organic odors caused by microbial breakdown.
For day-to-day smelly feet, a soak before bed followed by thorough drying can make a noticeable difference. Some people also dust dry baking soda inside their shoes, which absorbs moisture and continues neutralizing odors between wears. The effect is temporary, not curative. If the underlying cause is excessive sweating or a persistent fungal infection, the odor will return until the root issue is addressed.
Relieving Itch and Softening Rough Skin
Baking soda baths have a long history in dermatology as a soothing measure for itchy skin. The exact mechanism isn’t fully pinned down, but researchers have hypothesized that the pH shift created by sodium bicarbonate may inactivate molecules or pathways involved in itch signaling. Baking soda baths also appear to have mild keratolytic activity, meaning they help soften and loosen thickened, rough skin. This has been observed in patients with psoriasis, where baking soda baths helped reduce the thick, scaly plaques that characterize the disease.4Journal of Integrative Dermatology. Topical Integrative Treatments for Pruritus: A Comprehensive Review
For feet, this translates to two practical benefits. First, if your feet itch from fungal infection, contact dermatitis, or dry skin, a baking soda soak may offer short-term relief. Second, the mild keratolytic effect can help soften calluses and cracked heels, making it easier to file down dead skin afterward. This isn’t the same as an intensive chemical exfoliant, but for routine maintenance of rough feet, it’s a gentle and inexpensive option.
The Antibacterial Side
Beyond fungi, baking soda has demonstrated activity against bacteria relevant to skin health. Research into its effects on Staphylococcus aureus, a common and sometimes dangerous skin pathogen, found that sodium bicarbonate significantly reduced several of the bacterium’s virulence factors. These include its ability to form biofilms (the sticky colonies that make infections hard to clear) and its production of toxins like hemolysin. The bacteria also became more vulnerable to the immune system’s own killing mechanisms in the presence of baking soda.5Journal of Integrative Dermatology. Baking Soda and the Skin: A Review of Baking Soda in Dermatology
This is relevant to foot soaks because bacterial infections of the feet, while less common than fungal ones, do happen. Cracked skin between the toes or on the heel can let bacteria in. A baking soda soak won’t treat an active bacterial infection that needs antibiotics, but it may help keep the microbial environment on your feet a bit more controlled, especially if you’re prone to minor infections in areas where skin breaks down.
The Catch: Your Skin’s Acid Mantle
Here’s where the story gets more complicated, and where most home-remedy guides stop too early. Your skin maintains a naturally acidic surface, sometimes called the acid mantle, with a pH typically between 4.5 and 5.5. This acidity isn’t accidental. It’s a defense mechanism that discourages harmful bacteria and fungi, supports the skin’s barrier function, and helps retain moisture. Baking soda dissolved in water creates an alkaline solution with a pH around 8 to 9, which is a significant shift away from your skin’s natural state.
Research has linked disruption of the acid mantle’s pH balance to increased transepidermal water loss and greater vulnerability to infections and inflammatory skin conditions, including atopic dermatitis and acne.6Journal of Integrative Dermatology. From Discovery to Modern Understanding: The Acid Mantle in Dermatology In plain terms: repeatedly making your skin more alkaline can dry it out and, paradoxically, make it easier for the very pathogens you’re trying to fight to take hold.
This doesn’t mean a single foot soak will damage your skin. Healthy skin restores its acidic pH within a few hours after being exposed to alkaline substances, which happens every time you wash with regular soap anyway. The concern is about frequency and duration. Daily soaks over weeks, or very long soaks, push the skin’s recovery capacity harder. If you’re using baking soda soaks to manage a chronic condition like athlete’s foot, limiting them to a few times a week and moisturizing afterward is a reasonable approach. People with eczema or very sensitive skin on their feet should be more cautious, since their barrier is already compromised.
Does Baking Soda Actually Absorb Through the Skin?
A common assumption behind many topical remedies is that whatever you put on your skin eventually enters your bloodstream. For baking soda, the evidence says otherwise. A study that compared oral sodium bicarbonate supplementation against topical application (via a lotion containing sodium bicarbonate) found that the oral route significantly raised blood pH and bicarbonate levels within 10 minutes, while the topical application produced no measurable change in blood buffering capacity at all.7Human Kinetics Journals. Topical Sodium Bicarbonate: No Improvement in Blood Buffering Capacity or Exercise Performance
This tells you two things. First, you don’t need to worry about systemic side effects from a foot soak. Drinking large amounts of baking soda can cause electrolyte imbalances and metabolic alkalosis, but soaking your feet in it won’t shift your blood chemistry. Second, whatever benefits a baking soda soak provides are happening locally, at the skin surface. The effects are topical, which is fine for the uses described above, but it means the soak isn’t delivering some systemic health benefit throughout your body.
How to Actually Do a Foot Soak
Practical details matter more than most people think, because the concentration of baking soda affects how well it works and how much it stresses your skin. Based on the antifungal research, a concentration in the range of 10 to 20 grams per liter is where meaningful fungal inhibition starts. For a basin holding about 4 liters of warm water (enough to cover both feet), that works out to roughly 3 to 5 tablespoons of baking soda. You don’t need to be precise, but dumping in half a box is unnecessary and will just dry out your skin faster.
Temperature should be comfortably warm, not hot. Hot water strips oils from the skin and amplifies the drying effect of the alkaline solution. Soak for 15 to 20 minutes. Afterward, dry your feet thoroughly, especially between the toes, since moisture left in those crevices is exactly what fungi thrive on. Follow up with a moisturizer if your skin tends toward dryness. If you’re using the soak for fungal issues, consistency over a couple of weeks matters more than soaking for an hour once.
When a Soak Isn’t Enough
Baking soda foot soaks work best as supportive care and mild treatment for superficial problems. There are situations where they’re not sufficient:
- Worsening fungal infection: If athlete’s foot is spreading, blistering, or cracking open despite regular soaks, over-the-counter antifungal creams or prescription treatment are the next step.
- Established toenail fungus: As discussed, the nail plate blocks effective penetration. Oral antifungal therapy is usually necessary for clearing a nail infection.
- Diabetic feet: People with diabetes often have reduced sensation and compromised circulation in their feet. Soaking can macerate the skin and open the door to serious infections. If you have diabetes, check with your doctor before adding any soak to your foot care routine.
- Open wounds or deep cracks: Baking soda in an open wound stings and can irritate damaged tissue. If you have deep fissures on your heels or between your toes, healing those first is the priority.
- Persistent odor despite soaking: Foot odor that doesn’t improve with hygiene measures, including soaks, may indicate a condition called pitted keratolysis (a bacterial infection) or hyperhidrosis (excessive sweating), both of which benefit from targeted medical treatment.
Baking Soda Versus Epsom Salt
People often wonder whether to reach for baking soda or Epsom salt for their foot soak. The two do very different things. Epsom salt is magnesium sulfate, and its main reputation is as a muscle relaxant and general soak for soreness. The evidence for magnesium absorbing through the skin in meaningful amounts is thin, and Epsom salt has no documented antifungal activity comparable to baking soda’s. If your goal is to address foot fungus, odor, or itchy skin, baking soda is the better choice based on the available research. If your feet simply ache after a long day and you want the warm-water relaxation, either will do, because most of the soothing effect comes from the warm water itself.
Some people combine the two in the same basin, which is fine from a safety standpoint. They don’t react chemically with each other in any meaningful way. Whether combining them provides any advantage over using one alone hasn’t been studied.
Vinegar Soaks and the pH Puzzle
An interesting wrinkle in the home-remedy world is that vinegar foot soaks are also popular for treating athlete’s foot. Vinegar is acidic, with a pH around 2 to 3. Baking soda is alkaline. Both are recommended for the same condition, which sounds contradictory until you consider the mechanism. Fungi have a preferred pH range for growth, and pushing the environment far enough in either direction, more acidic or more alkaline, can inhibit them. The advantage vinegar has is that it nudges the skin back toward its natural acidic state rather than away from it, which is gentler on the acid mantle. The advantage baking soda has is that its antifungal activity has been more rigorously tested in laboratory settings with specific concentrations and fungal strains documented.
In practice, some people alternate between the two: a baking soda soak to knock back fungal growth, followed by a vinegar rinse to restore acidity. There’s no clinical trial proving this combination works better than either alone, but the logic is sound from a pH-management perspective. If you try this, use the baking soda soak first (since it’s alkaline and will be partially neutralized by the vinegar rinse afterward) and dry thoroughly between steps.
Why Dermatologists Remain Cautious
Despite the encouraging lab data, you won’t find many dermatologists enthusiastically prescribing baking soda foot soaks. The reason is the gap between in vitro and clinical evidence. The antifungal studies are conducted with precise concentrations in controlled conditions, and the real-world variables of foot anatomy, skin thickness, sweat, sock material, and patient compliance introduce a lot of noise. Proven antifungal medications like terbinafine and clotrimazole have been through large clinical trials showing they actually clear infections in living, walking humans, not just in lab dishes.
That said, baking soda is cheap, widely available, and carries very low risk when used sensibly. For someone with mild athlete’s foot who doesn’t want to start with medication, or for someone looking for an adjunct to standard treatment, it’s a reasonable thing to try. The worst likely outcome of a few weeks of foot soaks is slightly drier skin. And for odor and general foot freshness, the case is even simpler: it works, it’s safe, and it costs almost nothing.