1 By Nisid Hajari Nisid Hajari is a member of the Bloomberg View editorial board and author of âMidnightâs Furies: The Deadly Legacy of Indiaâs Partition,â to be published by Houghton Mifflin Harcourt on June 9. By Nisid Hajari Nisid Hajari is a member of the Bloomberg View editorial board and author of âMidnightâs Furies: The Deadly Legacy of Indiaâs Partition,â to be published by Houghton Mifflin Harcourt on June 9.
About Hives. Hives (or urticaria) are red raised bumps or welts on the skin. They can appear anywhere on the body and can look like tiny little spots or large interconnected bumps. Individual hives can last anywhere from a few hours to a week (sometimes longer), and new ones might replace those that fade.
Causes. The welts that come with hives arise when certain cells release histamine and other chemicals into your bloodstream. Doctors often can't identify the reason for this skin reaction, or why it sometimes turns into a long-term problem (chronic hives). But the skin reaction may be triggered by: 1  Pain medications. 2  Insects or parasites. 3  Infection. 4  Scratching. 5  Heat or cold. 6  Stress. 7  Sunlight.