It is not correct to assume that bites from harmful snakes are invariably fatal. Hospital case histories with definite identification of the biting snake show that in about half the cases there is little or no effect of the poison. This is understandable, considering the fact that snake bite on man is a purely defensive reaction.

The local symptoms of poisoning are distinctive and consist of pain, immediate swelling and later blisters and necrosis. These symptoms vary according to the species. Severe pain is felt after a cobra or viper bite, starting within few minutes of the bite in the case of the vipers and reaching a maximum in about 12 hours.

In the case of the cobra, swelling starts about 1 to 3 hours after the bite and reaches a maximum in 24 to 48 hours. Swelling of the whole limb occurs in viper and cobra bites and the swelling is tender in both cases. Poisoning by Krait may not cause local swelling.