Sodium Hydroxide (NaOH)

white powdery salt

What is sodium hydroxide (NaOH)?

Sodium hydroxide is sometimes called caustic soda or lye.  It is a common ingrediet in cleaners and soaps.  

At room temperature, sodium hydroxide is a white, odorless solid.  Liquid sodium hydroxide is colorless and has no odor. It can react violently with strong acids and with water.  Sodium hydroxide is corrosive.  NaOH can react with moisture from the air and may generate heat as it dissolves.  This heat can be enough to cause a fire if it is near flammable materials.

Sodium hydroxide is useful for its ability to alter fats.  It is used to make soap and as a main ingredient in household products such as liquid drain cleaners.  Sodium hydroxide is usually sold in pure form as white pellets or as a solution in water.

What are some uses of sodium hydroxide?

Sodium hydroxide is used in bar soaps and detergents.  Sodium Hydroxide is also used as a drain cleaner to unclog pipes.

Around 56% of sodium hydroxide produced is used by industry, with 25% of NaOH used in the paper industry.  Some other uses include fuel cell production, to cure food, to remove skin from vegetables for canning, bleach, drain cleaner, oven cleaner, soaps, detergent, paper making, paper recycling, aluminum ore processing, oxide coating, processing cotton fabric, pickling, pain relievers, anticoagulants to prevent blood clots, cholesterol reducing medications, and water treatment.

How might you be exposed to sodium hydroxide?

In the home, some household items like soaps or cleaners contain sodium hydroxide.  Accidental ingestion or skin contact with these cleaners could cause harmful exposure.

Some industrial workplaces use sodium hydroxide.  Here are some workplace exposure limits to NaOH in the air.

Workplace air exposure limits:

OSHA: The legal airborne
permissible exposure limit (PEL) is 2 mg/m3 averaged over an 8-hour work shift

NIOSH: The recommended airborne
exposure limit (REL) is 2 mg/m3 which should not be exceeded at any time

ACGIH: The threshold limit value
(TLV) is 2 mg/m3 which should not be exceeded at any time

How can you protect your family from exposure?

• Follow all precautions and instructions on product labels.

• Store and keep cleaning products out of the reach of children.

• Keep cleaning products in their original packaging.

• Wear latex or nitrile gloves when using products containing high concentrations of NaOH.

• Wear long sleeves and pants that cannot be degraded or deteriorated by sodium hydroxide to protect your skin.  Remove clothes carefully if they get wet to avoid spreading the sodium hydroxide on your skin.

What are potential harmful effects of sodium hydroxide exposure?

Sodium hydroxide is a potentially dangerous substance.  It can hurt you if it touches your skin, if you drink it or if you breathe it.  Eating or drinking sodium hydroxide can cause severe burns and immediate vomiting, nausea, diarrhea or chest and stomach pain, as well as swallowing difficulties. Damage to the mouth, throat and stomach is immediate.  Breathing it can cause severe irritation of the upper respiratory tract with coughing, burns and difficulty breathing.

The harmful effects of sodium hydroxide depend on several factors including the concentration of sodium hydroxide, length of time exposed, and whether you touched it, drank it or inhaled it.  Contact with very high concentrations of sodium hydroxide can cause severe burns to the eyes, skin, digestive system or lungs, resulting in permanent damage or death.  Prolonged or repeated skin contact may cause dermatitis.  Repeated inhalation of sodium hydroxide vapor can lead to permanent lung damage.

First Aid

In case of emergency, call 911.

Eye contact

  • Flush eyes with water for 30 minutes.
  • Lift upper and lower lids.
  • Remove contact lenses.

Skin Contact

  • Remove contaminated clothing.
  • Flush with water for 15 minutes.


  • Remove the person from exposure, if it is safe for you to do it.
  • If a person is unresponsive and not breathing normally, then begin CPR.


  • Never give anything by mouth to an unconscious person.
  • If the person is fully conscious and is not in respiratory distress, give them a cup of water to drink to dilute the sodium hydroxide.

Contact the Poison Center at 1-800-222-1222 for more information about exposure to sodium hydroxide.

Sodium hydroxide incidents in Tennessee

Back in 2010-2011, sodium hydroxide was reported as one of the ten most commonly spilled or released chemicals in Tennessee.  About 50% of these spills and releases occurred in warehouses or during transport.  About 75% of them were due to human error. 

Handling and storage

Spills and Emergencies – If employees are required to clean up spills, they must be properly trained and equipped.  The OSHA hazardous waste operations and emergency response standard (29 CFR 1910.120) may apply.

If sodium hydroxide is spilled or leaked, take the following steps:

Evacuate personnel and secure and control entrance to the area.

Eliminate all ignition sources.

For sodium hydroxide in solution, absorb liquids in dry sand, earth, or a similar material and place into sealed containers for disposal.

Collect solid material in the most convenient and safe manner and place into sealed containers for disposal.

DO NOT use water water or any WET METHOD to clean up NaOH.

Ventilate and wash area after cleanup is complete.

DO NOT wash into sewer.

It may be necessary to contain and dispose of sodium hydroxide as a hazardous waste.

Sodium hydroxide reacts with strong acids (hydrochloric, sulfuric or nitric), water, and moisture to rapidly release heat.

Sodium hydroxide reacts with metals (aluminum, lead, tin or zinc) to form flammable and explosive hydrogen gas.

Sodium hydroxide can form shock sensitive salts on contact with nitrogen containing compounds.

Sodium hydroxide is not compatible with oxidizing agents, chlorinated solvents, ammonia, and organic materials.

Store in original, tightly closed, containers in a cool, well ventilated area away from water and moisture.

Sodium hydroxide can attack iron, copper, plastics, rubber, and coatings.

Additional resources

Agency for Toxic Substances and Disease Registry (ATSDR)

Tennessee Poison Center 1-800-222-1222

National Institute of Occupational Safety and Health (NIOSH) 
Safety and Health Topic: Sodium Hydroxide:

National Library of Medicine (NIH)
Pub Chem - Sodium Hydroxide

Tennessee Department of Health - Healthy Homes

New Jersey Department of Health
Right to Know Hazardous Substance Fact Sheets in English and Spanish