There's not enough information to go by but sounds like the person might have a weakened liver and when Kambo is trying to push toxins out of the system, the liver has to process that.
A vegetarian diet; lots of fruits / vegetables, juicing / fasts or cleanses should help if that is the issue. We have some threads here on liver & gallbladder cleanse, herbal enemas, etc.
Milk Thistle's compound silymarin is shown to protect liver cells.
Most importantly, lots of water to flush the liver.