Oxalic acid is a poisonous, colorless substance. It is chemical known as a caustic. If it contacts tissues, it can cause injury.
This article discusses poisoning from swallowing oxalic acid.
This article is for information only. DO NOT use it to treat or manage an actual poison exposure. If you or someone you are with has an exposure, call your local emergency number (such as 911), or your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.
Seek immediate medical help. DO NOT make a person throw up unless told to do so by Poison Control or a health care professional.
If the chemical was swallowed, immediately give the person water or milk, unless instructed otherwise by a health care provider. DO NOT give water or milk if the person is having symptoms (such as vomiting, convulsions, or a decreased level of alertness) that make it hard to swallow.
Before Calling Emergency
The following information is helpful for emergency assistance:
- Person's age, weight, and condition
- Name of the product (ingredients and strengths, if known)
- Time it was swallowed
- Amount swallowed
However, DO NOT delay calling for help if this information is not immediately available.
Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.
This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.
What to Expect at the Emergency Room
The provider will measure and monitor vital signs, including temperature, pulse, breathing rate, and blood pressure. The person may receive:
- Airway support, including oxygen, breathing tube through the mouth (intubation), and breathing machine (ventilator)
- Blood and urine tests
- Camera down the throat (endoscopy) to see burns in the food pipe (esophagus) and stomach
- Chest x-ray
- CT or other imaging scan
- ECG (electrocardiogram, or heart tracing)
- Fluids through a vein (intravenous or IV)
- Medicines to treat symptoms
- Tube through the mouth into the stomach to aspirate remaining acid if the person is seen shortly after the exposure and a large amount was swallowed
For skin exposure, treatment may include:
- Surgical removal of burned skin (debridement)
- Transfer to a hospital that specializes in burn care
- Washing of the skin (irrigation), possibly every few hours for several days
Hospital admission may be needed. Surgery may be required if the esophagus, stomach, or intestines have developed holes (perforations) from exposure to the acid.
How well a person does depends on the amount of poison swallowed, how concentrated the poison is, and how quickly treatment was received. The faster a person gets medical help, the better the chance for recovery.
Severe damage to the mouth, gastrointestinal tract, or airway may occur and quickly cause death if not treated. Holes (perforation) in the esophagus and stomach may cause serious infections in both the chest and abdominal cavities, which may result in death.
Hoyte C. Caustics. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 148.
U.S. National Library of Medicine, Specialized Information Services, Toxicology Data Network website. Oxalic acid. toxnet.nlm.nih.gov. Updated April 16, 2009. Accessed January 15, 2019.
Review Date 12/21/2018
Updated by: Jacob L. Heller, MD, MHA, Emergency Medicine, Emeritus, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.