A brown recluse bite is usually painless, and symptoms may not appear for several hours. At that point, the area might become red, swollen, and tender. Most bites remain localized and heal within a few weeks without serious complications or medical treatment.
In more serious cases, a wound or lesion may form. It could have a dry, sinking bluish patch with irregular edges, a pale center, and redness on the outside. As the venom continues to destroy tissue, the bite wound may expand up to several inches over a period of days or weeks. It can eventually become a necrotic ulcer, which has dead tissues and leaves a deep scar.
Rarely, bites produce a systemic reaction (throughout the body) accompanied by fever, chills, dizziness, rash, or vomiting.