There are more than 12,000 species of ants. Although they can nearly all bite or sting, few cause significant local and/or systemic reaction in humans. Most ants are too small to effectively bite humans, and their sting is mild. However, the sting from harvester ants and fire ants can cause unpleasant symptoms and may lead to allergic reactions.

The normal reaction to many forms of ant bite/sting is localized contact urticaria (a skin rash with red, raised, itchy bumps). The normal reaction to a fire ant bite or sting is immediate pain and a red spot, followed a few hours later by a tender, itchy pustule that can last several days to weeks. It is common for a person to experience multiple stings.

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