Was just injected with 4ml of 8mg zofran (ondansetron). a 25g needle was used. injection site: thigh. i now have a numb lump at the injection site. why is that?

Injection site: Probably the medicine got injected superficially, it may get absorbed slowly, as it happened right after the injection that is what I can think of, if time lapsed from injection time, local inflammation or infection are other possible causes.

Injection: Often an injection will irritate the fat layer causing subcutaneous fat necrosis, which causes a lump that takes several weeks to resolve. If the area is red, tender and increasing in size; think of infection. All the best.