If you’ve spent any time researching hair growth online, especially on Reddit, you’ve probably seen folks talking about the “minoxidil bleach test.”

The test looks like this.

Pour a small amount of bleach into a cup, and then add a few drops of your minoxidil sample. In theory, if the minoxidil is authentic, the chemical reaction will turn the liquid a bright, sunny yellow or orange.

The video below shows this test in action.

The bleach test proposes an easy way to test your product at home. Mix a little bleach with your minoxidil, and if it turns yellow or orange, you’re good to go, right?

Well, not exactly. While the bleach test comes from a good place, it actually offers a false sense of security. Let’s break down why this viral test isn’t as reliable as it seems, and what you should do instead.

How Useful is the Minoxidil Bleach Test?

The short answer? It’s not very useful.

• It’s prone to false positives: Bleach is a harsh oxidizing agent. It reacts enthusiastically with a wide variety of chemical compounds, not just minoxidil. Counterfeiters know about the bleach test and can easily include cheap chemical fillers in fake products to make them change color and fool the test.

• Zero quantitative accuracy: The test cannot measure concentration or dosage. A bootleg batch containing a useless 0.5% minoxidil will turn yellow/orange just like an authentic 5% formula.

• Formula variations cause confusion: Minoxidil solutions come in different formulas. For example, some use non-PG (propylene glycol) bases, or have varying pH levels to be gentler on your scalp. These different ingredients can change the shade or speed of the color shift when mixed with bleach. This often causes perfectly legitimate, high-quality batches to “fail” the test and trigger unnecessary panic.

So, How Do You Know if It’s Authentic?

If the bleach test is a bust, you might be wondering how to check for authentic minoxidil.

The rise of the bleach test is a symptom of sketchy sourcing. It gained traction because third-party marketplaces (unverified sellers, shady storefronts, gray-market importers) are flooded with counterfeit cosmetics.

Sourcing your Minoxidil

If you already buy your minoxidil from a reputable vendor, mixing hair products with drain cleaner in your sink is completely unnecessary. Better physical checks exist anyway, such as checking lot numbers, verifying bottle seals, or checking if the liquid leaves behind characteristic minoxidil crystals as it dries.