Green hair is almost always caused by copper, not chlorine. The fix depends on how deep the discoloration goes, but most cases respond well to home remedies or a chelating shampoo within one or two washes. Here’s what’s actually happening and how to get rid of it.
Why Your Hair Turned Green
The widespread belief is that chlorine turns hair green. It doesn’t. Hair submerged in chlorinated water without copper ions does not turn green. The real culprit is copper dissolved in the water, which comes from pool plumbing, algaecides, and the water supply itself. Copper ions bond directly to the protein (keratin) in your hair, forming a copper-keratin complex that produces that telltale green tint. A 2020 study found that copper mainly binds to the sulfur-containing bonds in hair’s structure.
Chlorine plays a supporting role. It damages the outer layer of the hair shaft by stripping electrons from hair proteins, which makes it easier for copper to absorb deeper into each strand. So chlorine doesn’t cause the color, but it makes the problem worse by opening the door wider for copper to get in.
This is why blonde, bleached, and chemically treated hair turns green most easily. Bleaching and dyeing break apart the same sulfur bonds that copper targets, leaving the hair’s internal structure more porous and highly charged. That damaged hair absorbs unwanted metal ions like copper at a significantly higher rate than virgin hair. If you’ve lightened your hair and swim regularly, you’re essentially a magnet for green discoloration.
The Ketchup Method
This sounds absurd, but tomato ketchup or tomato paste is one of the most effective home fixes. It works on two levels. First, the acidity (from the vinegar in ketchup) helps break the chemical bond between copper and your hair. Second, red sits opposite green on the color wheel, so the red pigment in tomatoes neutralizes the green tone visually, the same principle hairstylists use with color-correcting toners.
Apply a generous amount of ketchup or tomato paste to dry or damp hair, focusing on the green sections. Leave it on for 10 to 20 minutes depending on how intense the green is. Rinse thoroughly, then shampoo and condition as normal. For mild cases, one application is often enough. Stubborn green may need a second round.
Other Home Remedies Worth Trying
If you’d rather not smell like a burger topping, a few other pantry items can help. Lemon juice and white vinegar both work as mild acids that loosen copper’s grip on hair proteins. Squeeze fresh lemon juice onto the green areas, let it sit for 5 to 10 minutes, then rinse. You can also mix equal parts white vinegar and water as a rinse after shampooing.
Crushed aspirin is another option. Dissolve about 5 aspirin tablets in a few ounces of clarifying shampoo, work it through your hair, leave it for 5 minutes, then rinse and condition well. The salicylic acid in aspirin acts as a mild chelator, helping to pull mineral deposits off the hair shaft. Baking soda paste (a few tablespoons mixed with water) can also help with light discoloration, though it’s less effective on deeper green.
Chelating Shampoos for Stubborn Cases
When home remedies only partially work, a chelating shampoo is the next step. These are different from regular clarifying shampoos. Clarifying shampoos strip product buildup and oil, but chelating formulas contain specific ingredients designed to grab onto metal ions and pull them off the hair. Look for ingredients like disodium EDTA, tetrasodium EDTA, citric acid, or ascorbic acid on the label. These compounds form chemical bonds with mineral deposits, essentially surrounding the copper ions so they rinse away with water.
Use the chelating shampoo on wet hair, work it in thoroughly, and let it sit for 3 to 5 minutes before rinsing. One wash often makes a noticeable difference. You can repeat once or twice a week until the green is gone, but don’t use chelating shampoo daily since it’s more stripping than regular shampoo and can dry out already-damaged hair. Follow with a deep conditioner every time.
Salon Demineralization Treatments
For severe or long-standing green discoloration that won’t budge at home, a salon can perform a demineralization treatment. The process is straightforward: a demineralizing solution is applied to the hair, left on for roughly 5 to 15 minutes, massaged or combed through for even coverage, then rinsed and followed with a cleansing wash. Some stylists add heat to speed up the process. The whole thing typically takes under 30 minutes.
This is especially worth considering if you have an upcoming color appointment. Mineral buildup on hair can interfere with dye results, causing uneven color or unexpected tones. Many colorists will run a demineralization step before applying new color to chemically treated hair that’s been exposed to hard water or pool water.
How to Prevent It From Happening Again
The easiest prevention step is wetting your hair with clean tap water before getting in the pool. Hair that’s already saturated absorbs less pool water, which means less copper exposure. For extra protection, apply a leave-in conditioner or a light hair oil (coconut oil works well) before swimming. This creates a physical barrier between the water and your hair shaft, reducing how much copper can penetrate.
After swimming, rinse your hair immediately. Don’t let pool water sit and dry on your strands, because that concentrates the copper as the water evaporates. A quick rinse with fresh water right after you get out makes a significant difference over time. If you swim frequently, using a chelating shampoo once a week as maintenance can prevent gradual green buildup before it becomes visible.
Swim caps offer the most complete protection, though they’re not watertight. They reduce water contact enough to make a real difference for daily or competitive swimmers. If you’ve bleached or color-treated your hair and swim multiple times a week, a cap combined with pre-wetting is the most reliable way to keep green from coming back.