Muscle spasms or stiffness after a bite or sting

Muscle spasms or stiffness can result from a toxic reaction to the venom of an insect or spider. This can be caused by a poisonous insect or spider or by multiple bites or stings from an insect or spider that is less toxic. A toxic reaction is most common with a black widow spider bite.

A muscle spasm, such as a charley horse, can occur for a variety of reasons unrelated to insect or spider bites. Most of the reasons are not serious.