Clinical Flowchart

Autopharmacological effects

Experimental and clinical observations suggest that the major systemic effects of envenoming are caused by endogenous catecholamines and acetylcholine, which are released in response to Atrax sp. and Hadronyche sp., Latrodectus sp., Phoneutria sp. venom. As these are transmitters of the sympathetic, parasympathetic and somatic nervous systems, the resulting clinical symptoms of envenoming are dealt with in the section "Neurological effects".

Local effects

Atrax sp. Hadronyche sp. Latrodectus sp. Loxosceles sp. Phoneutria sp. Various other labidognath spiders Bird spider-like species Theraphosidae sp. Various other mygalomorph spiders
Minutes to (hours)

Bird spider-like species Theraphosidae sp. Various other mygalomorph spiders		All other species

Skin: Dermatitis (urticaria, papular dermatitis); itching of the skin can persist for several months Eyes: conjunctivitis, keratitis, iritis, chorioretinitis		Local pain, swelling, redness

		Loxosceles sp.
		3-7 days

Chorioretinal scars		Necrosis

Haematological effects

Loxosceles sp.

1–3 days

Anaemia¹

1	Presentation of patients with systemic envenoming is with fever, malaise, vomiting, headache, rash and jaundice Haemolysis appears to occur rapidly or with a long delay after the bite (24–72 h to 2–3 days)

Neurological effects

Atrax sp.
Hadronyche sp.
Latrodectus sp.
Phoneutria sp.
Others (see

Minutes to hours

Cholinergic effects
Vomiting; sweating; hypersalivation and hyperlacrimation. Priapism.
Bradycardia, arterial hypotension, shock.
Adrenergic effects
Tachycardia, arterial hypertension, myocardial failure, pulmonary oedema (cardiogenic + ?non-cardiogenic component), cardiac ischaemia, shock, arrhythmias.

Neuromuscular dysfunction
Muscle fasciculations and spasms, local and generalised (Atrax sp. and Hadronyche sp.).
Abdominal rigidity, simulating acute abdomen (L. indistinctis, L. mactans).

Cardiovascular and pulmonary failure¹

Experimental and clinical observations suggest that the major systemic effects of envenoming are caused by endogenous catecholamines and acetylcholine, which are released in response to certain spider venoms. As these are transmitters in the sympathetic, parasympathetic and somatic nervous systems, the resulting clinical symptoms of envenoming are dealt with under neurological (neurotoxic) venom effects.

with cardiovascular and pulmonary effects secondary to autonomic nervous system effects.

Muscular effects

Not observed.

Cardiac effects

Not observed.

Renal effects

Not observed.