Cleaning chemicals you should never mix

Bleach and ammonia

What forms: chloramine gases.

Hypochlorite chlorinates ammonia to chloramines (mainly monochloramine), which escape as vapor. Poison Control notes chloramine is less volatile than chlorine gas, so it is less likely than chlorine gas to cause serious toxicity, but it is still harmful.

Where you might not expect it:

• some glass and window cleaners
• some interior and exterior paints
• urine (litter boxes, diaper pails, toilet bowls, pet-urine spots)

Symptoms: coughing, nausea, shortness of breath, watery eyes, chest pain, irritation of throat, nose and eyes, wheezing, in serious cases pneumonia and fluid in the lungs.

Do not use chlorine bleach on urine spots or in litter boxes/diaper pails without rinsing first, because urine contains ammonia compounds (WA DOH).

Bleach and vinegar or other acids

What forms: chlorine gas (which with moisture forms hydrochloric and hypochlorous acids); NJ DOH says vinegar + bleach gives harmful vapors including chlorine and chloramine.

Where you might not expect it:

• white vinegar
• lemon juice
• some toilet bowl cleaners
• lime, calcium and rust removers
• some dishwasher detergents
• some glass and window cleaners
• acidic drain cleaners (e.g. sulfuric acid)
• brick and concrete cleaners
• mildew stain removers (NJ DOH lists these as releasing chlorine gas with bleach)
• phosphoric-acid cleaners

Symptoms: burning, watery eyes and runny nose, eye, nose and throat irritation, coughing and breathing problems, at higher levels: chest pain, severe breathing difficulty, vomiting, pneumonia and fluid in lungs, very high levels can be fatal, skin contact with gas/concentrated solution: pain, inflammation, swelling, blistering/burns.

Bleach and rubbing alcohol

What forms: chloroform (plus other chlorinated organic byproducts; background chemistry: hypochlorite oxidizes isopropanol to acetone, which then undergoes the haloform reaction).

Symptoms: dizziness, nausea, headache, loss of consciousness (NJ DOH), AFRH/USFA describe the mixture as highly toxic.

Hydrogen peroxide and vinegar

What forms: peracetic (peroxyacetic) acid.

Symptoms: irritation of eyes, skin and lungs/respiratory tract, can be highly corrosive.

Safer way: Using them one after the other on a surface (wiping or rinsing between) is different from combining them in one container; never premix or store them together.

Two different drain cleaners

What forms: violent heat-producing reaction when acid (sulfuric/hydrochloric) and alkaline (sodium/potassium hydroxide) openers meet; splashing of corrosive liquid; toxic fumes, including chlorine gas if bleach is present.

Symptoms: irritation of eyes, mouth and throat, coughing or choking, chemical burns to skin and eyes.

If one drain opener did not work, do not pour in another; tell the plumber what is already in the drain.

Bleach and other cleaners

What forms: WA DOH says bleach reacts with these; NJ DOH says bleach + oven cleaner can produce chlorine gas and bleach + drain cleaner can create toxic chlorine gas.

Symptoms: eye, nose and respiratory irritation.

If you mixed products or breathed the fumes

1. Leave the area immediately and get to fresh air; open windows only if you can do so without staying in the fumes.
2. Call Poison Help at 1-800-222-1222 (free, confidential, 24/7 in the US; connects to the local poison center), or use the webPOISONCONTROL online tool.
3. Call 911 if the person has trouble breathing, collapses, has a seizure or cannot be woken; WA DOH says contact a health care provider or emergency services if symptoms develop.
4. Poison Control advice after chlorine gas: shower (about 20 minutes) and breathe steamy air to soothe airways, change clothes, and get medical care for breathing difficulty or serious symptoms.
5. Chemical in eyes or on skin: rinse with plenty of running water (Poison Control: 15–20 minutes for eyes).

How to avoid it

• Read and follow label directions; keep products in original labeled containers.
• Work with ventilation and take fresh-air breaks.
• Wear gloves and eye protection.
• Dilute bleach with room-temperature water (CDC); never with anything but water.
• Rinse a surface or toilet bowl thoroughly before switching products, so residues do not mix.
• Store chemicals locked/out of reach of children and pets; children 5 and under made up roughly 40–47% of cleaner/disinfectant calls to poison centers in early 2018–2020.