Here’s the thing: bleach is in a ton of household cleaners, and ammonia is in a lot of glass and surface cleaners. Mix them together — even accidentally — and they produce toxic gases called chloramines. According to the Washington State Department of Health and the New Jersey Department of Health, breathing in chloramine gas can cause shortness of breath, chest pain, wheezing, watery eyes, and irritation to your throat, nose, and eyes. In serious cases, it can lead to pneumonia and fluid in the lungs.
A medical study published on PubMed found that people who were exposed to this mixture needed prolonged hospital stays and were left with lasting lung damage even after they recovered. The researchers noted that this kind of poisoning may actually be a frequent cause of acute lung inflammation that often goes unrecognized — meaning people sometimes don’t realize what made them so sick. Note: this study is from 1985, but its findings align with current medical guidance and are still widely referenced.
One nuance worth knowing: Poison Control notes that chloramine gas is less volatile than chlorine gas (which forms when bleach mixes with acids instead of ammonia), meaning it’s somewhat less likely to cause serious toxicity than chlorine gas exposure. But “less likely” is not the same as “safe” — the hospital data makes that clear.
The most important thing you can do is check your labels before you mix or use multiple cleaners in the same space. If something says it contains bleach, don’t use it alongside any cleaner that contains ammonia. Glass cleaners are a common source of ammonia. When in doubt, rinse surfaces thoroughly between products and keep the space ventilated. If you smell something sharp or chemical and start feeling any of those symptoms, get fresh air immediately.
Bottom line: these are products sitting under nearly every sink in America, and most people have never been warned about this. Now you have been.