Never mix bleach and vinegar

Can you mix bleach and vinegar? No.

Never mix bleach and vinegar. Bleach is sodium hypochlorite, and adding vinegar or any acid makes it give off chlorine gas, which irritates your eyes, nose, throat and lungs. In a small bathroom with the door shut, that can build up quickly.

It is an easy mistake to make, especially when you are fighting mould in the shower. You have tried bleach, the black spots faded and came back. You have read that vinegar works better. Surely using both is twice as good? It is not. Mixing them does not make a stronger mould killer. It makes a gas you do not want to breathe, and it uses up the bleach in the process.

This page is about keeping you safe first. If you want the mould side of the story, our guides on whether vinegar kills mould and does bleach kill mould go into what each one really does.

People really do try this

If you have ever wondered about combining them, you are not alone. It comes up all the time when people are fed up with bathroom mould and looking for something that works. The usual ideas are:

• Using both at once, because bleach seems fast and vinegar seems to keep working for longer.
• Bleaching the mould off, then wiping vinegar over the same spot to keep it away.
• Assuming a little bit of each only makes a little bit of gas, so it must be fine.

That last one is the honest worry. A splash of each in a big, airy room may only give you a sharp smell and a cough. But you cannot judge the amount by eye, bathrooms are small, and people often clean with the door shut and the fan off. You are also bending close to the surface you are scrubbing. It is not worth the gamble.

What happens when you mix bleach and vinegar

In plain terms, without the equations:

• Household bleach is sodium hypochlorite dissolved in water. It is kept alkaline, because that keeps it stable in the bottle.
• Vinegar is an acid (acetic acid). When an acid meets bleach, it pulls the mixture away from alkaline.
• As the mixture becomes more acidic, chlorine gas is released and comes out of the liquid into the air. This is well established chemistry, not an internet scare story.

Chlorine gas has a sharp swimming pool smell and irritates the moist parts of your body: eyes, nose, throat and lungs. The more you make, and the less fresh air there is, the worse it gets.

Other cleaning products you should never mix with bleach

Vinegar is the one people ask about, but it is not the only danger. The safest rule is the simplest: never mix bleach with any other cleaning product.

The toilet is where most accidents happen

A lot of toilet cleaners are bleach. A lot of limescale removers and toilet descalers are acidic. Squirt one into a bowl that still has the other sitting in it and you have the same reaction as bleach and vinegar, right under your face. Flush between products and let the bowl clear before you add anything else.

Bleach and ammonia

Bleach and ammonia release chloramine vapour, which irritates the eyes and airways in a similar way. Ammonia is found in some glass cleaners and multi-surface sprays, so check the label before you reach for a second bottle.

“But I used them one after the other”

Using two products one after the other is only safe if the first one has gone before the second arrives. On a shower wall or a windowsill, “one after the other” often means spraying vinegar onto a surface that is still wet with bleach. That is mixing them, just on the wall instead of in a bucket.

If you do want to use more than one product, do it like this:

1. Use the first product exactly as the label says.
2. Rinse the surface thoroughly with clean water and wipe it down.
3. Ventilate the room: window open, extractor fan on, door open.
4. Rinse out cloths, sponges and buckets before using them with anything else.
5. Only then use the second product, and never on a surface that still has bleach on it.

Honestly, though, if one product has not worked, adding a second one on top rarely fixes it. Mould that keeps coming back usually has a moisture problem behind it, or it has grown into something porous like silicone or paint. Our guide to mould on sealant and grout covers when the real answer is to replace the sealant.

Warning signs of chlorine gas exposure

If you notice any of these while cleaning, stop and get out of the room:

Take extra care if anyone in the home has asthma or another lung condition, and keep children and pets well away from the room.

What to do if you have mixed bleach and vinegar

1. Step 1

   Stop and leave the room

   Do not keep cleaning and do not try to neutralise the mixture by adding something else. Get out and close the door behind you.

2. Step 2

   Get fresh air

   Go outside or to a room with open windows. If you can open the bathroom window from outside, or reach it without breathing the air, do that. Do not go back in to do it.

3. Step 3

   Rinse eyes or skin with plenty of water

   If the mixture splashed you or your eyes are stinging, rinse with plenty of clean running water. Take off any clothing that got splashed.

4. Step 4

   Get help if you need it

   If anyone has trouble breathing or chest pain, call 999. For advice, call NHS 111. Tell them what was mixed.

5. Step 5

   Wait until the air is clear

   Do not go back in until the smell has completely gone. Then, with the window open, rinse the mixture away with plenty of water.

Safer ways to treat mould in a bathroom

You do not need a cocktail of chemicals to deal with bathroom mould. You need one product used properly, and a plan for the moisture that is feeding it.

• Use one product at a time and follow the label: how long to leave it, whether to rinse, and what protection to wear.
• Ventilate: window open, extractor fan on, door open if you can.
• Wear gloves and eye protection whatever you use. Spray bottles splash.
• Pick something that needs no mixing. Plenty of products work on their own. Hydrogen peroxide at 6% or more is genuinely effective. A bleach-based spray such as HG works on tiles. Used on its own, with the window open, there is nothing wrong with that.

Where a hypochlorous acid spray fits

If you would rather avoid bleach fumes altogether, a hypochlorous acid mould remover spray like Mould Check is an option. It is near neutral (pH 6 to 7), COSHH free and gives off no harsh fumes, so it is safe to use with people at home, including children, pets and pregnant tenants. You spray it, leave it 10 minutes and wipe it clean, with no rinsing. It is safe on sealant, grout and painted walls. We still recommend gloves and eye protection when spraying.

Whichever product you choose, mould comes back unless you fix the moisture: condensation, poor ventilation or a leak. Our guide on how to get rid of mould on walls covers the cause as well as the clean up, and our COSHH guide explains why the safety label on a cleaning product matters.

Questions people ask about bleach and vinegar