What Happens When You Mix Bleach and Ammonia? The Chemistry of Chloramine Gas
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📋 What You'll Learn
This guide walks you through what happens when you mix bleach and ammonia? the chemistry of chloramine gas with detailed instructions.
Two of the most common bottles under an American sink will make a toxic gas if they meet. Most people know that in a general way. In a 2020 CDC survey of 502 US adults, only 58% identified "bleach should not be mixed with ammonia" as true. Less well known: the gas comes in three forms, the mix decides which one you get, and many US water utilities make the mildest of the three on purpose.
What happens when you mix bleach and ammonia?
Household bleach is a solution of sodium hypochlorite. Clorox's own safety data sheet lists it at 5–10% by weight, with the exact figure withheld as a trade secret, and gives the pH as about 12. Household ammonia cleaners are dilute ammonia in water, typically 5% to 10% according to the federal ATSDR. Pour one into the other and the hypochlorite hands a chlorine atom to the ammonia:
The product is monochloramine, NH2Cl. It is what people mean when they say "chloramine gas," although there are really three chloramines, and at bathroom-sink concentrations some of it leaves the liquid as a sharp, choking vapor. The sodium hydroxide stays behind in the puddle, so treat the leftover liquid as caustic.
The reaction is fast. The EPA's criteria document for chloramines gives a rate constant of 6.1 × 106 M-1s-1 at 25 °C for the core reaction between ammonia and hypochlorous acid, and notes that between pH 6.5 and 10 the rate was too fast to measure. In practical terms, the gas starts forming as soon as the two liquids touch. There is no safe window to "just rinse it down."
If you have just mixed them: stop, leave the room, and get into fresh air. Don't try to neutralize the puddle with anything else. Call Poison Help at 1-800-222-1222, or 911 if anyone is having trouble breathing. Full steps are below.
The bleach and ammonia reaction: three kinds of chloramine gas
Ammonia has three hydrogen atoms, and chlorine can replace each of them in turn. The EPA lays out the sequence, with hypochlorous acid (HOCl, the more reactive form of chlorine in bleach solutions) doing the work:
Each step is much slower than the one before it. Using the EPA's rate constants (6.1 × 106, 3.4 × 102 and 2.1), the second step's rate constant is about 18,000 times smaller than the first, and the third's about 160 times smaller than the second. Which product you end up with depends on two things: how much chlorine there is relative to ammonia, and the pH.
pH
The EPA document states that monochloramine is the only chloramine formed when the water is above pH 8 and there is less hypochlorite than ammonia. It also states that "at pH >7.5, no trichloramine is found, regardless of the ratio of chlorine to ammonia." Drop the pH and the balance shifts toward dichloramine. The EPA's table for equal amounts of chlorine and ammonia at 25 °C:
| pH | Monochloramine (NH2Cl) | Dichloramine (NHCl2) |
|---|---|---|
| 4 | 0% | 100% |
| 5 | 13% | 87% |
| 6 | 57% | 43% |
| 7 | 88% | 12% |
| 8 | 97% | 3% |
Bleach sits at about pH 12, so a straight bleach-and-ammonia spill mostly makes monochloramine. The dangerous twist is the third bottle. Vinegar, lime and rust removers and some toilet-bowl cleaners are acids. Add one to the mix and you drag the pH down toward the dichloramine end of that table (and, at low enough pH with excess chlorine, trichloramine), and the acid also frees chlorine gas from the bleach directly. We covered the acid side on its own in the chlorine gas mixing mistake.
The chlorine-to-ammonia ratio
Water engineers measure this as the weight of chlorine per weight of ammonia nitrogen. A 2007 EPA issue paper says monochloramine predominates when that ratio is 5:1 or less. As it climbs from 5:1 toward 7.6:1 the water approaches breakpoint chlorination, where the chloramines and ammonia are destroyed and turn into nitrogen gas and hydrochloric acid. Above 7.6:1 you get free chlorine plus nitrogen trichloride. The EPA's older criteria document puts the observed breakpoint closer to 10:1 at pH 7, so treat 7.6:1 as the theoretical number. Utilities run at 3:1 to 5:1 specifically to stay away from it.
Nitrogen trichloride
NCl3 is a bright yellow liquid when pure, and PubChem lists it as explosive. Acids push a bleach-and-ammonia mix toward dichloramine and trichloramine, the more irritating chloramines, and also release chlorine gas from the bleach. The table below summarizes the three.
| Compound | Formula | CAS | Molar mass | Notes (PubChem / EPA) |
|---|---|---|---|---|
| Monochloramine | NH2Cl | 10599-90-3 | 51.47 g/mol | Unstable; solvent-free material decomposes violently. The main product above pH 7.5. |
| Dichloramine | NHCl2 | 3400-09-7 | 85.92 g/mol | Unstable; decomposes to nitrogen and other products, which accounts for much of the breakpoint reaction. |
| Nitrogen trichloride | NCl3 | 10025-85-1 | 120.36 g/mol | Yellow liquid, boils at 71 °C; explosive, sensitive to impact, light and ultrasound. Absent above pH 7.5. |
Chloramine gas symptoms and what it does to your lungs
The Washington State Department of Health lists the symptoms as coughing, nausea, shortness of breath, watery eyes, chest pain, irritation of the throat, nose and eyes, wheezing, pneumonia and fluid in the lungs; New Jersey's health department notes the last two occur in serious cases. The Tennessee Poison Center explains why: when inhaled, chloramines react with the moisture in the respiratory tract and release ammonia and hydrochloric acid along with oxygen free radicals. Low doses cause mild irritation. High doses injure the lining of the airway and can lead to pneumonitis and pulmonary edema.
Published case reports go back to the 1980s:
A 27-year-old woman mixed 500 mL of 4–5% household ammonia with the same amount of 5% bleach in a small, poorly ventilated bathroom. She had burning eyes and throat, coughing, nausea and vomiting, and developed pneumonitis. She recovered without permanent lung damage.
Physicians reported three cases of life-threatening toxic pneumonitis from household ammonia and bleach. Each patient had a long hospital stay and was left with residual changes on chest X-ray. The authors warned it "may be a frequent cause of acute pneumonitis that is not well recognized."
In San Antonio, Texas, 36 male soldiers were exposed during a barracks "cleaning party" and treated at Wilford Hall and Brooke Army Medical Centers. Ten days later 36 female soldiers were exposed the same way. Both groups had mixed liquid bleach and ammonia. The authors described it as the largest emergency-department series of chloramine inhalation reported.
A woman with an undiagnosed brain tumor mixed bleach and ammonia and died while cleaning her bathroom. The authors wrote that deaths are very rare and that, to their knowledge, it was the first death reported from chloramine gas.
How toxic is chloramine gas?
Most home exposures are mild and clear within hours, but severe lung injury and deaths are documented. Poison Control (poison.org) notes that chloramine is less volatile than chlorine gas, so it is less likely to cause serious toxicity. The Pittsburgh Poison Center followed 216 home exposures to chlorine and chloramine gas: 200 of them had symptoms clear within 6 hours, 145 were treated at home, and only one needed admission for continued breathing trouble. That patient already had a chronic lung condition and a respiratory infection.
At national scale the numbers add up. A 2024 study in Clinical Toxicology counted 85,104 chlorine and chloramine gas exposures reported to US poison centers from 2015 to 2022. Exposures rose 61%, from 8,385 in 2015 to 13,503 in 2022, with the biggest jump (38.3%) between 2019 and 2020, the first year of COVID-19, when poison-center calls about cleaners spiked. 84.9% happened at the person's own home. 619 people were admitted to intensive care and 26 died. An earlier author manuscript of the same study, which counted 75,186 adult exposures, classed 19,722 (28%) of the single-substance cases as chloramine gas; most of the rest were chlorine gas. The deaths are reported for the group as a whole.
In the case reports above, the worst outcomes involved small, closed rooms or people with pre-existing illness. The concentration you breathe is what matters, which is why ventilation and distance do more than anything else.
There is no US workplace exposure limit for chloramine or nitrogen trichloride. NIOSH and OSHA publish limits for the two parents, and the World Health Organization has a reference value for trichloramine in indoor pool air:
| Substance | Limit | Value | Source |
|---|---|---|---|
| Ammonia | NIOSH REL / OSHA PEL / IDLH | 25 ppm TWA (35 ppm short-term) / 50 ppm TWA / 300 ppm | NIOSH Pocket Guide |
| Chlorine | NIOSH REL / OSHA PEL / IDLH | 0.5 ppm ceiling (15 min) / 1 ppm ceiling / 10 ppm | NIOSH Pocket Guide |
| Monochloramine | US occupational limit | None established | No NIOSH Pocket Guide entry |
| Trichloramine (NCl3) | WHO reference value, pool air | 0.5 mg/m³ (500 µg/m³) | Westerlund et al., Ann Occup Hyg 2015, citing WHO 2006 |
What to do if you accidentally mixed bleach and ammonia
1. Get out. Leave the area immediately and breathe fresh air. Take kids and pets with you. Poison Control's first instruction is exactly this.
2. Call for help. Poison Help is 1-800-222-1222, free and open 24 hours. Call 911 if anyone is having trouble breathing or seems seriously ill; Washington State's health department says to contact a health care provider or 911 for anyone with symptoms after a chemical mix. CDC's chlorine guidance notes that after low exposures, symptoms may show up later, so call even if you feel fine at first.
3. Rinse off. Poison Control suggests a 20-minute shower if possible, breathing the steamy air to soothe the airway.
4. Don't neutralize it. Don't add vinegar, more bleach, baking soda or anything else to the puddle. Adding an acid (vinegar, toilet-bowl cleaner) or more bleach makes it worse.
5. Air it out before you go back. Open windows and run an exhaust fan from outside the room if you can reach the switch safely. Clean up the liquid only after the room has aired out, with plenty of water, wearing gloves.
The Tennessee Poison Center describes hospital treatment as supportive: oxygen, airway support, bronchodilators, and treatment for fluid in the lungs.
Household products that contain ammonia
Nobody sets out to mix bleach and ammonia. It happens because the ammonia is in something that doesn't say "ammonia" on the front.
- Glass cleaners. Poison Control calls glass cleaners the most common household product with ammonia. SC Johnson's ingredient sheet for Windex Original Glass Cleaner lists ammonium hydroxide as its cleaning agent. Poison Control also notes that only some Windex formulas contain it, so read the label on the one you own.
- Urine. NASA's 1971 analysis of human urine found 9,300–23,300 mg/L of urea and 200–730 mg/L of ammonia, and noted that when urine sits, bacteria break the urea down and give off "large amounts of ammonia." That is why bleaching a toilet, a urinal, a diaper pail or a pet accident can make chloramine without any cleaner involved. Washington State lists urine alongside glass cleaners as a source.
- Paints and fertilizer. Washington State lists some interior and exterior paints. Poison Control lists fertilizers and potting soil with fertilizer.
- Swimming pools. Covered below. The ammonia comes from swimmers.
The rule that covers every case: bleach goes on alone, onto a surface that has been rinsed with water, and gets rinsed off before the next product. Clorox's own SDS lists toilet bowl cleaners, rust removers, acids and products containing ammonia as incompatible.
Your tap water is chloraminated on purpose
The EPA states that "more than one in five Americans uses drinking water treated with chloramines," and that utilities have used them since the 1930s. The utility adds ammonia to chlorinated water in a controlled ratio (an EPA issue paper says utilities normally hold 3:1 to 5:1 chlorine to ammonia nitrogen by weight) to make monochloramine, the mildest of the three, on purpose.
They do it for two reasons. Chloramine lasts longer than free chlorine as water travels through miles of pipe, so there is still a residual at the far end of the system. And it produces far fewer regulated byproducts. In one EPA-cited test on Ohio River water, monochloramine at 10 mg/L cut trihalomethane formation by 90.7–99.9% compared with chlorine at the same dose.
The difference between your tap and your bathroom floor is concentration and control:
| Tap water | Bleach + ammonia spill | |
|---|---|---|
| Chlorine source | Metered chlorine, a few mg/L | Bleach at 5–10% (50,000+ mg/L) |
| Ammonia | Metered to a 3:1–5:1 weight ratio | Whatever was in the other bottle |
| Typical chloramine | 0.5–2 mg/L (WHO) | Uncontrolled, some of it as vapor |
| Limit | EPA legal max 4.0 mg/L; WHO guideline 3 mg/L | None |
| Where it goes | Stays dissolved in closed pipes | Into the air of a small room |
Two groups do have to remove it. The EPA says chloramine must be taken out of water used in kidney dialysis machines, because that water contacts blood directly, although dialysis patients can drink it normally. Aquarium fish are also sensitive because chloramine enters their bloodstream through the gills, which is why aquarium stores sell conditioners for it. If you want the full picture of what residual your utility is maintaining and what happens when it drops, see what a boil water notice actually means.
That "chlorine smell" at the pool is chloramine
The CDC puts it plainly: "If you smell 'chlorine' at the place you swim, you are probably smelling chloramines." Chlorine in the pool combines with sweat, urine, skin cells, deodorant and makeup that come off swimmers and forms chloramines. The WHO adds that the ammonia comes largely from the breakdown of urea. The CDC notes that chloramines that off-gas are heavier than air, so they settle on top of the water, right where swimmers breathe. That sharp indoor-pool smell, and the red eyes, are the same family of compounds as the bathroom accident, at much lower concentration.
Does bleach and ammonia make mustard gas or hydrazine?
It is not mustard gas. The idea is all over the internet. Sulfur mustard, the World War I agent, is bis(2-chloroethyl) sulfide, C4H8Cl2S (PubChem CID 10461). It needs carbon and sulfur. Bleach and ammonia contain neither in any meaningful amount. What they make is chloramine, which is dangerous enough on its own terms.
Hydrazine is a stretch. Many pages say mixing bleach and ammonia makes hydrazine, the rocket fuel. The chemistry is real in industry: the Raschig process makes hydrazine from sodium hypochlorite and ammonia via chloramine. PubChem describes the industrial conditions. In the Olin Raschig process, chloramine is added to a 30-fold molar excess of anhydrous ammonia at 20–30 MPa and 130 °C, and the liquor that comes out holds only 1–2% hydrazine hydrate. PubChem notes separately that the reaction needs additives such as gelatin or glue to suppress side reactions. We found no primary source measuring hydrazine from a household mix. The thing that hurts people in a bathroom is the chloramine.
What not to mix with bleach
| Bleach plus | What forms | Common products |
|---|---|---|
| Ammonia | Chloramines (NH2Cl, NHCl2, NCl3) | Glass cleaners, some multi-surface cleaners, urine |
| Acids | Chlorine gas (Cl2) | Some toilet-bowl cleaners, lime and rust removers, vinegar, muriatic acid, some dishwasher rinses |
| Rubbing alcohol | Chloroform and other chlorinated compounds (NJ Department of Health) | Isopropyl alcohol |
The New Jersey Department of Health's hazard alert describes a restaurant worker with asthma who opened a dishwasher, was overcome by fumes from a mix of Lime-A-Way and bleach inside it, and later died. Mixing isn't only a bleach problem, either. The viral hydrogen peroxide and vinegar "super cleaner" makes peracetic acid; we explained that one in mixing hydrogen peroxide and vinegar.
And what should ammonia never be mixed with? Bleach first, and any other product that contains hypochlorite, such as chlorine pool shock (calcium hypochlorite).
Storing sodium hypochlorite and ammonium hydroxide
We sell sodium hypochlorite and ammonium hydroxide at strengths well above what's in a household bottle, so the same rule applies with more force: store them apart and never let them meet.
| Product | Strengths we stock | Grade |
|---|---|---|
| Sodium hypochlorite | 1%, 2%, 3%, 5.25%, 6%, 8.25%, 10%, 12.5% | No grade designation |
| Ammonium hydroxide | 5%, 10%, 15%, 20%, 29% | Technical Grade and ACS Grade |
Our 12.5% hypochlorite carries more than twice the hypochlorite of a 5.25% household bottle, and our 29% ammonium hydroxide is roughly three to five times the strength of a 5–10% household ammonia. Everything in this article applies with more force at those strengths. Every order comes with a Safety Data Sheet, and all of ours are online. Section 7 covers handling and storage and Section 10 lists incompatible materials. Read both before the product goes on a shelf next to anything else. For the ammonia side in detail, see our 29% ammonium hydroxide ACS grade guide.
Storage rule of thumb: keep hypochlorite away from acids and ammonia, keep containers closed, and don't use the same scoop, funnel or bucket for both. A trace of one left in a bucket is enough to start the reaction when the other goes in.
Need the SDS before you buy?
Every Alliance product ships with a Safety Data Sheet, and a Certificate of Analysis is available on request at no charge. Sodium hypochlorite and ammonium hydroxide ship from Taylor, Texas, in sizes from a single quart to a 330-gallon IBC tote.
Browse Safety Data SheetsReferences & Authoritative Sources
- Drinking Water Criteria Document for Chloramines — U.S. EPA Office of Water, ECAO-CIN-D002, 1994. Reaction sequence, rate constants, pH distribution, THM reduction.
- The Effectiveness of Disinfectant Residuals in the Distribution System — U.S. EPA TCR Issue Paper, 2007. 5:1 and 7.6:1 ratios, breakpoint.
- Chloramines in Drinking Water — U.S. EPA. "More than one in five Americans."
- National Primary Drinking Water Regulations — U.S. EPA. Chloramines MRDL 4.0 mg/L.
- Common Health Questions Related to Monochloramine — U.S. EPA, 2009. Dialysis and aquariums.
- Chloramines chemical fact sheet — World Health Organization, 2022. Typical 0.5–2 mg/L; guideline 3 mg/L.
- PubChem CID 25423: Monochloramine; CID 61437: Nitrogen trichloride; CID 9321: Hydrazine; CID 10461: Sulfur mustard — NCBI, U.S. National Library of Medicine.
- Atalla A, et al. Trends in chlorine and chloramine gas exposures reported to United States poison centers — Clinical Toxicology 2024;62(9):589–595.
- Gharpure R, et al. Knowledge and Practices Regarding Safe Household Cleaning and Disinfection — CDC MMWR 2020;69:705–709.
- Mrvos R, Dean BS, Krenzelok EP. Home exposures to chlorine/chloramine gas — Southern Medical Journal 1993;86(6):654–7.
- Reisz GR, Gammon RS. Toxic pneumonitis from mixing household cleaners — Chest 1986;89(1):49–52.
- Pascuzzi TA, Storrow AB. Mass casualties from acute inhalation of chloramine gas — Military Medicine 1998;163(2):102–4.
- Cohle SD, et al. Fatal chloramine gas intoxication — Forensic Science International 2001;124(2–3):137–9.
- Chlorine Gas and Is Windex Toxic? — Poison Control, National Capital Poison Center.
- Bleach Mixing Dangers — Washington State Department of Health.
- Hazard Alert: Mixing Cleaners — New Jersey Department of Health.
- Bathrooms and nerve agents — Tennessee Poison Center, Vanderbilt University Medical Center, 2018.
- Chloramines and Pool Operation and Preventing Eye Irritation from Pool Chemicals — CDC Healthy Swimming.
- Chlorine fact sheet — CDC Chemical Emergencies. Ammonia and Chlorine — NIOSH Pocket Guide to Chemical Hazards.
- Medical Management Guidelines for Ammonia — ATSDR. Household ammonia 5–10%.
- Westerlund J, et al. Exposure to trichloramine in Swedish indoor swimming pools — Annals of Occupational Hygiene 2015.
- Putnam DF. Composition and Concentrative Properties of Human Urine — NASA CR-1802, 1971.
- Clorox Regular-Bleach Safety Data Sheet — The Clorox Company, 2020. 5–10% sodium hypochlorite, pH ~12, incompatibles. Windex Original Glass Cleaner ingredient sheet — SC Johnson Professional.
- Laakso M, et al. British Medical Journal 1982;285(6348):1086 — bathroom case, as summarized in the EPA 1994 criteria document, p. VI-1.
- Chang A, et al. Cleaning and Disinfectant Chemical Exposures and Temporal Associations with COVID-19 — CDC MMWR 2020;69:496–498.
- Ammonia: History, Usage and Safety — Poison Control, National Capital Poison Center.
Frequently Asked Questions
What happens if you mix bleach and ammonia?
They react to form chloramine gas (mainly monochloramine, NH2Cl) and sodium hydroxide. The vapor irritates the eyes, nose, throat and lungs and can cause pneumonia and fluid in the lungs at high exposure.
Can you mix bleach and ammonia?
No. Mixing them makes chloramine gas. Use bleach on its own, rinse, and only then use another product.
What two chemicals should never be mixed?
For household cleaning, the two best-known dangerous pairs are bleach with ammonia (chloramine gas) and bleach with an acid such as vinegar or toilet-bowl cleaner (chlorine gas).
What should ammonia never be mixed with?
Bleach, and any other product that contains hypochlorite, such as chlorine pool shock (calcium hypochlorite).
How toxic is chloramine gas?
Most home exposures are mild and resolve within hours: in a Pittsburgh Poison Center study, 200 of 216 people had symptoms clear within 6 hours. But severe lung injury and deaths are documented, especially in small unventilated rooms and in people with lung disease.
How long does chloramine gas stay in the air?
There is no fixed time. The puddle keeps giving off vapor until it is diluted and cleaned up, and the air clears only as fresh air replaces it. Leave, ventilate from outside if you can, and don't go back until the smell is gone. Symptoms in mild cases usually fade within about 6 hours, though CDC's chlorine guidance notes that low exposures can produce delayed symptoms.
What should I do if I breathed it in?
Get to fresh air, call Poison Help at 1-800-222-1222, and call 911 for any trouble breathing. A warm shower helps rinse the skin and soothe the airway.
Does bleach and ammonia make mustard gas?
No. Sulfur mustard (C4H8Cl2S) requires carbon and sulfur. Bleach and ammonia make chloramine.
What is another name for chloramine gas?
Monochloramine or chloramine (NH2Cl). With more chlorine you also get dichloramine (NHCl2) and nitrogen trichloride, also called trichloramine (NCl3).
Is chloramine in tap water dangerous?
The EPA allows up to 4.0 mg/L in drinking water, and typical levels are 0.5–2 mg/L. EPA's position is that water meeting its standards is safe to drink, but chloramine must be removed for kidney dialysis machines and aquariums.
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