What Is Sodium Sesquicarbonate?
Sodium sesquicarbonate, also known as trisodium hydrogendicarbonate, is a mineral salt that combines the properties of both baking soda and washing soda. It forms naturally in certain lake beds but for cosmetic use it is usually manufactured by blending sodium carbonate with sodium bicarbonate in water, then allowing the solution to crystallize and dry into a fine powder. The ingredient first gained popularity in household cleaning and bath products thanks to its gentle alkalinity. Formulators soon noticed that the same qualities that help clean surfaces could also refresh skin, leading to its adoption in personal care items. Today you can spot sodium sesquicarbonate in bath bombs, effervescent foot soaks, clay masks, deodorant powders, toothpaste, solid cleansers and some mild exfoliating scrubs.
Sodium Sesquicarbonate’s Cosmetic Benefits/Uses
In skin and body care formulas sodium sesquicarbonate serves several helpful roles.
- Buffering: It stabilizes the pH of a product so the formula stays gentle on skin and active ingredients remain effective throughout the product’s shelf life.
- Bulking: Its light crystalline structure adds volume to powders and solids, which can improve texture and help spread other active ingredients more evenly.
- Cleansing: Mild alkalinity helps lift dirt, oil and surface buildup without harsh surfactants, making it useful in bath soaks, toothpaste and powder cleansers that aim for a fresh but not stripped feel.
Who Can Use Sodium Sesquicarbonate
Sodium sesquicarbonate is generally best for normal, combination or oily skin because its mild alkalinity helps remove excess oil and debris. People with very dry or highly sensitive skin may find it too lifting, as the alkalinity can disrupt an already fragile moisture barrier and leave skin feeling tight. When used in well balanced formulas or rinse-off products most users experience no discomfort.
The ingredient is a mined and synthetically recreated mineral salt with no animal-derived components so it is suitable for vegans and vegetarians.
Current safety data does not flag any specific issues for pregnant or breastfeeding women. Still, this is not medical advice; those who are pregnant or nursing should check with a healthcare professional before introducing any new cosmetic product to be extra sure it aligns with individual needs.
Sodium sesquicarbonate is not known to increase photosensitivity so it will not make skin more prone to sunburn. It is also unlikely to interfere with common active ingredients, though highly acidic products may neutralize its buffering benefit.
Potential Side Effects/Adverse Reactions
Responses to topical sodium sesquicarbonate differ from person to person. The points below cover potential effects that could occur, but most users will not experience them when the ingredient is used at appropriate levels in a well formulated product.
- Dryness or tightness especially on already dehydrated skin
- Temporary stinging or tingling if applied to freshly shaved or broken skin
- Mild redness or irritation in people with very sensitive or compromised skin barriers
- Eye discomfort if powder or foam accidentally gets into the eyes during use
- Rare allergic response presenting as itching swelling or rash
- pH imbalance for other actives possibly reducing the effectiveness of low-pH acids if mixed directly
If any of these reactions occur discontinue use and seek advice from a qualified healthcare provider.
Comedogenic Rating
Rating: 0/5 – Sodium sesquicarbonate is a water-soluble mineral salt that rinses away completely and contains no oils or waxes that could block pores. Because it dissolves fast and does not leave a residue, it has virtually no potential to cause comedones.
This makes the ingredient a safe choice for people who are prone to acne or frequent breakouts.
Worth noting: its alkalinity can dry skin if overused, and very dry skin can sometimes compensate by overproducing oil. Keeping the overall formula balanced and following with moisturizer helps avoid this indirect route to congestion.
Summary
Sodium sesquicarbonate provides buffering, bulking and cleansing in cosmetic formulas. It moderates pH so products stay gentle, adds airy volume to powders which helps them spread evenly and uses mild alkalinity to loosen dirt and oil for a fresh feel.
While not the most talked-about ingredient, it shows up steadily in bath soaks, solid cleansers, toothpaste and other rinse-off products because it is affordable, vegan friendly and easy to formulate with.
Current research and long use in household and personal care items support its reputation for safety when used at normal cosmetic levels. Still, skin can be unpredictable, so it is smart to patch test any new product that contains sodium sesquicarbonate before full application.