The Three-Ingredient Spray Dermatologists Have Known About for Years
Hypochlorous acid spray is trending for acne, eczema, and post-workout skin — here’s what it does, how it works, and who should use it.
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Most of us have been conditioned to believe that effective skincare means a long ingredient list. So when something with three components, water, salt, and hypochlorous acid, starts showing up on derm TikTok and in the bags of celebrity makeup artists, the internet pays attention.
On a recent episode of the ‘Live + Well’ podcast, host Melissa Magsaysay sat down with Amy Liu, founder of Tower 28 Beauty, to break down the science behind the brand’s cult SOS Rescue Spray and why an ingredient with decades of clinical use is only now finding its way into everyday routines.
What is Hypochlorous Acid (HOCl)?
Hypochlorous acid (HOCl) is not new. What’s new is being able to buy it at Sephora. Liu says that the ingredient had been used in hospital wound care settings for years... and the reason is pretty straightforward.
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Because it works. “It literally is an antibacterial and an anti-inflammatory,” Liu explains. “It’s been known to kill staph and many other bacteria, which are a lot of what skin conditions prey on.”
NAD+ precursors to Hypochlorous Acid (HOCl) and ectoin, these 12 skincare ingredients help support hydration, strengthen the skin barrier, and improve overall skin health.
The Science of Stabilizing HOCl for Sensitive Skin
For anyone managing eczema, rosacea, or acne, Liu says the dual action matters. Inflammation may be the root of most skin issues, but in her view, bacteria is what makes them spread and worsen.
The reason it took so long to reach consumers comes down to chemistry. “The ingredient existed, but it’s not been commercially available because it’s unstable,” Liu explains. Tower 28 worked with chemists to stabilize it for facial use, dialing in the pH and concentration before bringing it to market.
Hypochlorous acid spray was developed for reactive skin, but at this point, a lot of people reaching for it have never thought of themselves as having a skin condition at all. Liu noticed it first through the makeup artist community. “I was with a bunch of celebrity makeup artists, and they had no idea that the products are for sensitive skin,” she says. “They’re like, we just keep it because it works.”
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And for people who don’t have sensitive skin and want to use it because it helps prevent breakouts and calm irritation, according to Lui, that’s about as honest a review as you can get.
How to Use HOCI? From Post-Workout to Retinol Sandwiching
The use cases she describes are refreshingly unglamorous. Planes. Post-workout. The five minutes before trying a new retinol. That last one she approaches with what she calls a sandwiching method: spray first to calm the skin, apply the active, then seal with moisturizer so nothing harsh lands on a barrier that’s already been compromised. “The goal,” she says, “is to avoid having anything harsh hit your skin directly.”
The post-workout piece makes more sense once Liu explains what’s actually happening. Sweat sitting on skin shifts its pH, quietly turning it into what she calls “almost a breeding ground for bacteria” before you’ve noticed anything is wrong. A quick mist resets that before it becomes a problem.
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And that’s really the point she keeps coming back to. The answer to inflamed or reactive skin, in Liu’s view, is rarely another product. It’s more often about understanding what your skin is asking for. In this case, that turns out to be something with three ingredients that hospitals have relied on for decades.
Click here to listen to the full episode.
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