Dear Nicole

All emergency wards of major hospitals would stock anti snake venom. We usually use a "general" one that works for most snakes but for certain snakes like the boomslang it is important to treat specifically.The National Health Laboratory Services (NHLS) produces a polyvalent antivenom that is effective against all venomous snakes common in Southern Africa except for the boomslang (Dispholidus typus) and the twig snake (Thelotornis capensis). The NHLS produces a monovalent antivenom specific for the boomslang but none is available for the twig snake.

If possible one should always try to take the (dead) snake with to the emergency room. ( And try not to crush the head - it makes identification very difficult)
Dr Bets