The Ultimate Guide to Hypochlorous Acid Spray

There’s a reason hypochlorous acid spray keeps showing up in skincare conversations, whether the topic is acne, eczema, or scars. It’s not a passing trend, but a natural compound your body already makes, with over 200 years of medical use behind it.

While hypochlorous acid comes in several forms, spray is the most common option for skincare. In this guide, you’ll find out what hypochlorous acid is, get a quick history of how it’s been used, take a closer look at what research says about its benefits, and learn why spray is the go-to format for skincare.

What Is Hypochlorous Acid?

Hypochlorous acid (or HOCI) is a molecule your body makes. Every time you get a cut or fight off an infection, your immune system produces it to help kill germs.

It’s made from hydrogen, oxygen, and chlorine, which are the same ingredients found in bleach. Studies suggest, though, that hypochlorous acid spray can be far more effective than bleach at killing bacteria. Another advantage is that hypochlorous acid doesn’t irritate skin or eyes the way bleach can.

So what does hypochlorous acid do, exactly? Unlike antibiotics, which usually target one specific process inside a germ, hypochlorous acid attacks germs from the outside by breaking down their protective outer layer.

On top of that, hypochlorous acid has anti-inflammatory properties. That’s why it’s now used to help with wound healing, itchy skin, and conditions like seborrheic dermatitis and eczema.

The tricky part: how well hypochlorous acid kills germs and whether it may irritate your skin depends on its pH level and the formula’s stability.

The History of Hypochlorous Acid

Hypochlorous acid was first made over 200 years ago in a small village near Paris called Javel, which is where the French word for bleach, “Eau de Javel,” comes from.

Back then, nobody even knew germs caused disease, but doctors noticed that HOCl helped prevent wound infections and common post-childbirth infections.

Later, during World War I, hypochlorous acid spray was used to treat everything from routine wounds to gangrene and scarlet fever. For a long time, chlorine-based solutions like this were the standard antiseptic, though keeping them stable was difficult.

In the 1940s, London hospitals used aerosolized HOCl to help control the spread of germs. Around that time, scientists discovered that immune cells produce hypochlorous acid naturally every time your body needs to fight something off.

The COVID-19 pandemic gave it a second wind as researchers looked for new ways to use it directly on the body, not just as a surface disinfectant.

When to Use Hypochlorous Acid Spray

Today, hypochlorous acid can show up in a lot of places you might not even expect. These include:

• Disinfecting hospitals and other surfaces
• Cleaning and healing wounds
• Keeping food and water safe
• Caring for sick patients
• Tending to animals
• Treating eye infections
• Rinsing nasal passages

When it comes to skincare, you’ll usually find hypochlorous acid in a spray, a gel, or a rinse. Hypochlorous acid spray is the most common option, and it’s clear why: you can spritz it directly onto irritated skin without having to rub it in. Gels, though, tend to stick around a little longer, which makes them a good fit for conditions like seborrheic dermatitis. Rinses, in turn, are primarily used to clean wounds.

Hypochlorous Acid Spray for Skin: How It Can Be Used

Now let’s get to the part you’re probably most curious about—using hypochlorous acid spray for skin. These are three skin concerns it may help with, backed by science.

Before we dive in, OnSkin is always here to spot all the allies and foes for your skin, whatever type or condition it is.

1. It takes on acne

If breakouts brought you here, let’s see whether hypochlorous acid spray for acne actually works. Breakouts usually start with certain bacteria on your skin. They produce enzymes that react with your natural oils, creating the fatty acids that clog your pores. Hypochlorous acid can fight those bacteria.

In fact, it may work just as well as benzoyl peroxide, one of the most common acne treatments. One clinical study found that both options were more effective than a placebo. While people using HOCl didn’t report any side effects, benzoyl peroxide can sometimes leave skin feeling irritated or dry.

2. It eases itching in eczema

For anyone with eczema, itching is often the hardest part. Since eczema-prone skin tends to be sensitive, many people look for gentle treatment options.

That’s where hypochlorous acid comes in.

Researchers tested it on people with eczema to see if it could help with itching. One group used hypochlorous acid, while another didn’t use any treatment. The HOCl group saw a difference after just 72 hours: nearly two-thirds felt less itchy, and their skin looked better overall, with less redness, dryness, and flaking. The treatment was also gentle, with only one case of mild, temporary dryness reported.

3. It helps fade scars

Raised, thickened scars can be stubborn and difficult to fade. They can show up anywhere on the body, including the face, and silicone gel is one of the most common options for care. Could HOCl make it even more effective?

A 16-week study suggests that it can. Researchers compared silicone gel alone with silicone gel combined with hypochlorous acid in 40 people. Both groups saw their scars improve, but the HOCl combination worked better. Scars faded more, and doctors reported better results overall.