Hypochlorous acid (HOCl) for skin is the latest "miracle ingredient" buzzing in the skincare world. Fans tout its transformative HOCl benefits from scar healing to acne. But what is this molecule, how does it work, and is it actually deserving of all the hype? Let’s break down everything the chemists think you should know before adding a Hypochlorous acid spray to your routine.
What is Hypochlorous Acid?
HOCl is a weak acid and potent pro-oxidant that our body naturally produces as a defense mechanism against infection. Think of it as a tiny little suicide bomber disinfectant: HOCl binds with the unsaturated lipid layer of microbes, disrupting their cellular integrity, thus killing the microbes.
In fact, it’s such a powerful disinfectant, hypochlorous acid is actually widely used in the medical field before it became a popular skincare ingredient. Many hospitals will make HOCl fresh, onsite by running an electric current through low-concentration salt water. This freshly made HOCl water is a highly effective and gentle disinfectant. There’s even data that shows that at concentrations as low as 20 to 200 ppm, it can effectively kill norovirus in 10 minutes of contact time.
Hypochlorous Acid’s Stability Problem
Of course, nothing is perfect. HOCl’s biggest catch is that it’s extremely unstable. It makes sense from a biological standpoint. HOCl does its job, then degrades into harmless byproducts. However, this presents a significant challenge in making it a reliable skincare product. Here are all the factors a brand has to consider to ensure their HOCl product works:
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pH dependent: HOCl is most stable around slightly acidic pH of 4 to 6.5
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Water purity: the smallest impurity in water can affect HOCl stability!
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Sensitivity to Light: UV exposure can quickly degrade hypochlorous acid. We’re talking about depletion on the order of hours
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Sensitivity to Heat: HOCl also doesn’t do well in heat. It does best in cool room temperature to refrigerator temperature. This fussy molecule doesn’t enough like freezer temperature!
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Doesn’t play nicely with others: Metal ions, oxygen, and excess organic compounds can also deplete HOCl
In summary? Formulating shelf-stable HOCl takes some real chemistry prowess as well as thoughtful packaging choices.
Hypochlorous Acid Skin Benefits
Given how incredibly fussy this molecule can be, why even try? It all boils down to there’s a long list of skin benefits that it’s linked to from soothing, itch-relief, to even acne, eczema, psoriasis. If you shop for HOCl products, it’s practically touted as the do-everything do-anything skincare superstar. But sadly, for the sheer amount of skin benefits associated with hypochlorous acid, the data doesn’t seem to quite keep up. Let us dive into the actual studies:
Hypochlorous Acid for Scar Care
Pharmaceuticals company Sonoma has done most of the work studying hypochlorous acid for scar care under their Microcyn line. In one of their studies, their HOCl scar gel was tested against a more common place 100% silicone gel on hypertrophic and keloid scars. While subject satisfaction was similar between the two groups, HOCl showed some extra benefits for fresher scars.
Chemists’ Takeaway: In our opinion, the data here shows that HOCl can be helpful for healing fresh wounds - but not so convinced on existing scars.
Hypochlorous Acid for Soothing and Eczema Relief
There are a few small studies that looked at HOCl for itch relief, specifically those with eczema. In one 3 day study, 20 out of 30 participants are treated with HOCl and 10 untreated. After 3 days, it showed itch relief compared to the untreated group in both expert evaluation as well as participant self evaluation.
In another study, 17 participants with mild to moderate eczema applied an HOCl gel 3 times a day for 2 weeks. This study also showed itch relief over time.
Chemists’ Takeaway: Hypochlorous acid products heavily claims soothing. Based on the data alone, we’d say this is the most inconclusive claim.
Hypochlorous Acid for Acne
This is where we really expect hypochlorous acid to really shine. Though tied to many different skin biological pathways, at the end of the day, hypochlorous acid is a well-established antimicrobial. In in vitro studies, HOCl can kill a broad range of bacteria, their biofilms, and even fungi. This strong antimcrobial activity is why HOCl sprays are a fan favorite for acne-prone skin.
Though there isn’t any direct data of HOCl action on C. acnes, there’s a clinical study that compared a hypochlrous acid solution to benzoyl peroxide for acne. Both groups showed comparable reduction in inflammatory lesions.
Chemists’ Takeaway: it’s pretty impressive to get similar results as acne superstar benzoyl peroxide (BPO). However, the study didn’t share the concentration of BPO in the study. So all we can say here is that - there is promise, but hard to really make a fair comparison to more well-established active ingredients.
Best Hypochlorous Acid Spray: Chemists’ Shopping Guide
Shopping for hypochlorous acid sprays can be quite callenging. We ourselves tested the top 3 brands you might encounter: Tower28, Magic Molecule, and Prequel. Below you’ll find a snapshot of their ingredient lists and price point:
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Tower28 SOS Daily Rescue Facial Spray ($28/4oz): Water, Sodium Chloride, 0.015% Hypochlorous Acid.
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Prequel Universal Skin Solution ($17/4oz): Water (Aqua)*, 0.02% Hypochlorous Acid, Sodium Chloride, Muriatic Acid. *Electrolyzed Water
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Magic Molecule Skin Spray ($13.49/3.4oz): Hypochlorous acid 0.018%, Ionized water 99.918%, Sodium chloride (salt) 0.06%, Hypochlorite ion 0.004%
Ultimately, given how unstable hypochlorous acid is, it’s a no brainer to gun for one that is the most stable. Unfortunately, without making stability testing data public, you can’t, it’s hard for us to recommend an absolute clear winner of the bunch. So we would like to point your attention to secret option number 4 - Briotech.
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Briotech Topical Skin Spray ($9.99/2oz): Water, Sodium Chloride, 0.014% Hypochlorous Acid
In our research, Briotech was essentially the only brand that disclosed some of their testing. In their shared stability test, their hypochlorous acid cleaner has a half life of over 450 days. So for those of you curious about what hypochlorous acid really does for your skin, Briotech seems to be one of the more reliable starting points.
How to Use Hypochlorous Acid in Your Skin Routine
If you’re intrigued by the science, claims, and testimonials of hypochlorous acid, here are some of our chemists’ top tips for incorporating it into your skincare routine:
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Apply on clean face: this should be the first step in your skincare routine!
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Contact time matters: we’re typically not people who’d harp on strict “must wait x minute claims”, but when it comes to taking full advantage of HOCl’s antimicrobial properties, letting it sit on your skin undisturbed for 5 to 10 minutes will make a huge difference.
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Layer per usual after: you might see a lot of misinformation online about layering faux pas after HOCl. But the reality is, this isn’t an active ingredient that’s meant to stay potent for 8+ hours. In fact, most HOCl clinicals use it liberally throughout the day.
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Mind the storage condition: HOCl stability is the biggest challenge. Cool dark places is the way to go. This is the type of product that can really benefit from a skincare fridge. The catch? Fridge temperature will do the trick - avoid the freezer
Key Takeaway
HOCl is an intriguing ingredient that has been super bussy. While it has solid antimicrobial properties, other claims remain less convincing based on existing clinical studies. If you’re battling an angry breakout or flare-up, it might be worth a try. Just remember, store in cool, dark places. Use generously, frequently and see how skin responds. We would think of this as a “use in a pinch” product rather than a daily routine staple.
References
Block, M. S., & Rowan, B. G. (2020). Hypochlorous acid: a review. Journal of Oral and Maxillofacial Surgery, 78(9), 1461-1466.
Ishihara, M., Murakami, K., Fukuda, K., Nakamura, S., Kuwabara, M., Hattori, H., ... & Yokoe, H. (2017). Stability of weakly acidic hypochlorous acid solution with microbicidal activity. Biocontrol science, 22(4), 223-227.
Gold, M. H., Andriessen, A., Bhatia, A. C., Bitter Jr, P., Chilukuri, S., Cohen, J. L., & Robb, C. W. (2020). Topical stabilized hypochlorous acid: The future gold standard for wound care and scar management in dermatologic and plastic surgery procedures. Journal of cosmetic dermatology, 19(2), 270-277.
Fukuyama, T., Martel, B. C., Linder, K. E., Ehling, S., Ganchingco, J. R., & Bäumer, W. (2018). Hypochlorous acid is antipruritic and anti‐inflammatory in a mouse model of atopic dermatitis. Clinical & Experimental Allergy, 48(1), 78-88.
Natarelli, N., Nong, Y., Maloh, J., & Sivamani, R. (2022). Hypochlorous acid: Applications in dermatology. Journal of Integrative Dermatology.
Tirado-Sánchez, A., & Ponce-Olivera, R. M. (2009). Efficacy and tolerance of superoxidized solution in the treatment of mild to moderate inflammatory acne. A double-blinded, placebo-controlled, parallel-group, randomized, clinical trial. Journal of dermatological treatment, 20(5), 289-292.
