Apart from any other specific medicine to an illness constitutional medicine is the best preventive medicine. Usually a patient on constitutional medicine does not develop illness and enjoy good health.
As times it has been seen that a specific medicine for example Euphrasia taken for conjunctivitis precipitates the illness rather than stimulating the illness. For the same reason it is advisable to take constitutional treatment as a preventive treatment instead of a specific medicine. Eupatorium Perfoliatum is one specific medicine for prevention of chiken gunya fever when taken during epidemic.