Definition

Nitric acid is a poisonous clear-to-yellow liquid. It is a chemical known as a caustic. If it contacts tissues, it can cause severe damage, such as burning, on contact.

This article discusses poisoning from swallowing or breathing in nitric 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 the local emergency number (such as 911), or the 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.

Poisonous Ingredient

Nitric acid

Where Found

• Fertilizers
• Substances used to clean metals (such as gun barrels)

Note: This list may not be all inclusive.

Symptoms

Symptoms from swallowing nitric acid may include:

• Abdominal pain - severe
• Burns to skin or mouth
• Drooling
• Fever
• Mouth pain - severe
• Rapid drop in blood pressure (shock)
• Throat swelling, which leads to breathing difficulty
• Throat pain - severe
• Vomiting, bloody

Symptoms from breathing in (inhaling) nitric acid may include:

• Bluish-colored lips and fingernails (cyanosis)
• Chest tightness
• Choking
• Coughing
• Coughing up blood
• Dizziness
• Low blood pressure
• Rapid pulse
• Shortness of breath
• Weakness

If the poison touches your skin or eyes, you may have:

• Blisters
• Burns
• Pain
• Vision loss

Home Care

Seek medical help right away. 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. Give 4 to 6 ounces (120 to 180 milliliters) of milk of magnesia, if possible.

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.

If the person breathed in the poison, immediately move them to fresh air.

Before Calling Emergency

The following information is helpful for the emergency responders:

• The person's age, weight, and condition
• The name of the product (and ingredients and strength, if known)
• The time it was swallowed or inhaled
• The amount swallowed or inhaled

However, DO NOT delay calling for help if this information is not immediately available.

Poison Control

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 to see burns in the airway (bronchoscopy)
• Camera down the throat (endoscopy) to see burns in the food pipe (esophagus) and stomach
• Chest x-ray
• CT (computerized axial tomography) scan
• ECG (electrocardiogram, or heart tracing)
• Fluids through a vein (intravenous or IV)
• Medicines to treat symptoms
• Tube through the nose into the stomach to suction (aspirate) any remaining acid if the person is seen shortly after the exposure and a large amount was swallowed

Note: Activated charcoal does not effectively treat poisoning by acid.

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 necessary to continue treatment. Surgery may be required if the esophagus, stomach, or intestines have developed holes (perforation) from exposure to the acid.

Outlook (Prognosis)

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.

Cancer of the esophagus is a high risk in people who survive after ingesting nitric acid. 

Perforation may lead to potentially serious infection and shock, which may be fatal. Permanent injury and disability may occur.

References

Hoyte C. Caustics. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 143.

Pfau PR, Benson M. Foreign bodies, bezoars, and caustic ingestions. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 28.