Several other members of the genus Latrodectus are not commonly associated with latrodectism including the cosmopolitan brown widow (L. geometricus).

The main symptoms are generalized muscle pain, stomach cramps, nausea and vomiting.

The venom acts on nerves causing the massive release of the neurotransmitters acetylcholine, norepinephrine, and GABA.

[13] Latrotoxin acts on presynaptic nerve membranes (See Chemical synapse) and through the cell's signalling protein (calcium-independent receptor of alpha-latrotoxin CIRL).

[citation needed] There are no tests required to diagnose widow spider bites, or latrodectism symptoms.

However, without a history of contact, the diagnosis may be missed as symptoms overlap with a variety of other serious clinical syndromes such as tetanus or acute abdomen.

Blood values are typically unimportant but may be needed to show myocarditis or dehydration from vomiting.

[4][5] People who have been bitten by a black widow spider are recommended to seek professional medical assistance for symptoms.

Death from latrodectism is rare and primarily occurs in adults with cardiovascular disease or children.

[21] Despite a frequent reference to youth and old age being predisposing factors, it has been demonstrated that young children appear to be at the lowest risk for a serious bite, perhaps owing to the rapid use of antivenom.

[22] Bite victims who are very young, old, hypotensive, pregnant, or who have existing heart problems are reported to be the most likely to develop complications.

Of the bites reported in the United States from 2001 to 2005, approximately 31% were treated in a health care facility, 0.5% had major complications, and none were fatal.