Mixing lemon juice and baking soda triggers an acid-base reaction that produces carbon dioxide gas (the fizzing), water, and a compound called sodium citrate. That fizzy reaction is real chemistry, but many of the health and beauty claims built around it don’t hold up nearly as well as the cleaning uses do.
Why It Fizzes
Lemon juice is acidic, with a pH around 2.35, mostly from citric acid. Baking soda is a base with a pH around 9. When they meet, the acid neutralizes the base and releases carbon dioxide gas, which is the rush of bubbles you see. What’s left behind is water and sodium citrate, a mild salt. This is the same basic type of reaction that happens inside a baking soda volcano at a science fair.
The key point: once the fizzing stops, you no longer have a strong acid or a strong base. You have a mostly neutral, slightly salty liquid. That matters for understanding why some of the popular uses work and others don’t.
Where the Combination Actually Works: Cleaning
As a household cleaner, the lemon-and-baking-soda pairing has genuine advantages. Lemon juice cuts grease, dissolves soap scum, and breaks down hard water deposits. It also has natural antiseptic and antibacterial properties. Baking soda, meanwhile, is a gentle abrasive. Mixed into a paste, it can scrub surfaces without scratching the way harsher scouring powders might.
Together, they’re effective on kitchen counters, cutting boards, sinks, and stovetops. The fizzing action can help loosen stuck-on food. You can also use the paste on stained mugs or thermoses. For deodorizing, baking soda absorbs odors while lemon leaves a fresh scent behind. Cornell Cooperative Extension lists this combination among recommended homemade cleaning products.
Heartburn Relief: Short-Lived and Risky
Drinking baking soda dissolved in water is an old home remedy for heartburn, and adding lemon juice is a popular variation. The logic seems sound: baking soda neutralizes stomach acid, which dulls the burning sensation quickly. But the relief tends to be brief, and the mixture can actually make things worse.
The carbon dioxide produced by the reaction increases pressure inside your stomach. That extra pressure raises the chance that stomach contents push back up into your esophagus, re-triggering the very burning you were trying to stop. This rebound effect is especially likely after a large meal, if you ate quickly, if you’re already bloated, or if you lie down soon after eating.
Even without lemon, baking soda is high in sodium and easy to overuse because it’s cheap and works fast. Repeated use can lead to fluid retention and electrolyte imbalances. It can also mask a pattern of frequent reflux that needs a more reliable treatment plan rather than a quick fix from the pantry.
Teeth Whitening: More Harm Than Help
One of the most popular DIY beauty tips online is brushing your teeth with a lemon juice and baking soda paste. The idea is that baking soda’s mild abrasiveness scrubs stains while lemon juice brightens. In practice, this is one of the riskier things you can do to your teeth.
Lemon juice, at a pH around 2, is acidic enough to erode tooth enamel. A 2015 study confirmed that lemon juice eats away at enamel, and unlike skin or nails, enamel does not regenerate. Once it’s gone, it’s gone permanently, leaving teeth more vulnerable to decay, sensitivity, and discoloration.
Some people assume baking soda’s alkalinity cancels out the lemon’s acidity, making it safe. There’s no evidence that baking soda fully neutralizes the acid in this context, especially when you’re spreading the mixture directly onto tooth surfaces. The brief contact time during brushing isn’t enough for complete neutralization, and even partial acid exposure can damage enamel over repeated use.
Skin Care: A pH Mismatch
Your skin naturally sits at a weakly acidic pH of about 5.7. This “acid mantle” protects against bacteria, locks in moisture, and keeps the skin barrier functioning properly. Both lemon juice and baking soda disrupt it, just in opposite directions.
Lemon juice’s low pH can cause irritation, trigger hyperpigmentation (especially in darker skin tones), and increase sensitivity to UV light. Baking soda’s higher pH can strip the skin’s barrier, leading to dryness, excess oil production, and breakouts. Mixing them together doesn’t reliably land at a skin-safe pH. The neutralization is imprecise, and you’re likely left with patches of both acid and base on your face before they fully react.
The result is that a homemade lemon-and-baking-soda face mask can irritate skin from both ends of the pH spectrum simultaneously. Dermatologists generally consider it a poor substitute for products specifically formulated to match the skin’s natural acidity.
The “Alkalizing Your Body” Claim
A persistent online claim suggests that drinking lemon water with baking soda can “alkalize your blood” and prevent diseases, including cancer. This fundamentally misunderstands how the body works. Your blood pH is tightly regulated between 7.35 and 7.45 by your kidneys and lungs. Drinking a slightly alkaline beverage doesn’t shift that number in any meaningful way. If it could, you’d be in serious medical trouble.
A 2020 review published in PubMed noted that despite “specious claims” that baking soda and lemon juice are miracle cures for everything from cancer to infectious diseases, the body’s acid-base balance is maintained by sophisticated internal systems, not by what you drink. The therapeutic uses of acid-base management that actually exist in medicine involve carefully controlled clinical treatments for specific conditions, not kitchen remedies.
What It’s Good For, and What It Isn’t
The combination genuinely shines as a cleaning agent. The acid dissolves grime, the base provides gentle scrubbing power, and the fizzing helps lift debris. It’s cheap, nontoxic compared to chemical cleaners, and effective on everyday kitchen and bathroom messes.
For anything you put on or in your body, the picture is much less favorable. The heartburn relief is temporary and can backfire. The teeth whitening damages enamel permanently. The skin treatments disrupt your skin’s protective barrier. And the alkalizing claims simply aren’t supported by how human physiology works. The fizzy reaction looks dramatic, which might be part of why people trust it to do dramatic things. But once the bubbles settle, you’re left with salty water.