Bites are relatively rare, due to their docile nature and the fact that their range is mainly limited to rainforest areas. Nevertheless, when it does occur it should always be considered a serious medical emergency. Even an average bite from an average sized specimen is potentially fatal.
The venom itself is not considered particularly toxic. In mice, the LD50 is 0.8–5.0 mg/kg IV, 2.0 mg/kg IP and 5.0–6.0 mg/kg SC. However, the venom glands are enormous and produce the largest quantities of any venomous snake. Yield is apparently related to body weight, as opposed to milking interval. Brown (1973) gives a venom yield range of 200–1000 mg (of dried venom), A range of 200–600 mg for specimens 125–155 cm in length has also been reported. Spawls and Branch (1995) state that from 5–7 ml (450–600 mg) of venom may be injected in a single bite.
A study by Marsh and Whaler (1984) reported a maximum yield of 9.7 ml of wet venom, which translated to 2400 mg of dried venom. They attached "alligator" clip electrodes to the angle of the open jaw of anesthetized specimens (length 133–136 cm, girth 23–25 cm, weight 1.3–3.4 kg), yielding 1.3–7.6 ml (mean 4.4 ml) of venom. Two to three electrical bursts of five seconds each were enough to empty the glands. The snakes used for the study were milked 7–11 times over a 12-month period, during which they remained in good health and the potency of their venom remained the same.
Based on how sensitive monkeys were to the venom, Whaler (1971) estimated that 14 mg of venom would be enough to kill a human being: equivalent to 0.06 ml of venom, or 1/50–1/1000 of what can be obtained in a single milking. Branch (1992) suggested that 90–100 mg would be fatal in humans. Marsh and Whaler (1984) wrote that 35 mg would be enough to kill a man of 70 kg (1/30 of the average venom yield).
In humans, a bite causes rapid and conspicuous swelling, intense pain, severe shock and local blistering. Other symptoms may include uncoordinated movements, defecation, urination, swelling of the tongue and eyelids, convulsions and unconsciousness. Blistering, bruising and necrosis may be extensive. There may be sudden hypotension, heart damage and dyspnoea. The blood may become incoagulable with internal bleeding that may lead to haematuria and haematemesis. Local tissue damage may require surgical excision and possibly amputation. Healing may be slow and fatalities are not uncommon