Boric acid is a chemical substance that is also known as orthoboric acid or sassolite. It is used as an ingredient in many products, including insecticides, antiseptics and plant food. Boric acid is naturally found in low concentrations in water, fruits and vegetables. However, in higher concentrations the substance can be harmful.


Boric acid is an odorless white powder. When dissolved in water, the solution is a weak acid. The chemical is stable and does not require any special storage measures. It is not considered a hazardous waste when discarded.

Human Toxicity

Boric acid is a poison, although not an extremely toxic one. Symptoms of boric acid poisoning are diarrhea, blue-green vomit and a bright red skin rash. Boric acid can irritate the eyes, skin and respiratory tract. Repeated exposure can result in dermatitis. The product may be absorbed through the skin through cuts or wounds.

Medical Uses

At one time, the substance was used as a disinfectant in nurseries and to disinfect and treat wounds. Patients who received this treatment repeatedly got sick and some died. As a result, boric acid is no longer commonly used in medical products. It is still found in some vaginal suppositories used to treat yeast infections, but this is not a standard treatment.

Pesticide Use

Boric acid was registered as a pesticide in the United States in 1948. Currently, more than 180 registered pesticide products contain boric acid. Boric acid is mixed with a feeding attractant, such as sugar water, to create a bait for insects, such as ants, cockroaches, termites and silverfish. Alternatively, dry powder is sprayed into cracks where it leaves a fine layer of dust. When insects walk through the powder, it sticks to their legs. The insects ingest the powder when they groom themselves. The acid acts as a stomach poison for insects, causing death due to starvation and dehydration in approximately three to 10 days after ingestion. Boric acid is generally considered safe when used in this manner.

Other Uses

Boric acid interrupts photosynthesis in plants and suppresses algae in swimming pools and sewer systems. It can be used as a wood preservative, by controlling fungi in wood products. Boric acid is also found as ingredient in plant food, dish washing liquid and stain remover.


Wear safety glasses when handling solutions of boric acid if there is a possibility of splashing the chemical in your eyes. Wear protective gloves or thoroughly wash hands after handling. If ingested, do not induce vomiting, but seek medical attention immediately. Keep boric acid products away from children and pets.