Standard hydrogen peroxide should not be ingested, according WebMD. An extremely small amount of food-grade hydrogen peroxide can be ingested with a glass of water when used as an alternative therapy for various conditions, according to the National Capital Poison Center.
Regular hydrogen peroxide can be harmful if swallowed, according to WebMD. If ingestion occurs, the individual should promptly contact a poison control center or emergency room.
The ingestion of small amounts of hydrogen peroxide generally does not cause health problems beyond an upset stomach and vomiting, according to the National Capital Poison Center. When an individual ingests a large amount of hydrogen peroxide, severe stomach irritation and tissue burns can occur.