The invention provides the use of at least one plant selected from plants of the family Zingiberaceae in the preparation of a medicament for use in the treatment or prophylaxis of allergic diseases. The plant is optionally selected from the genera Siphonochilus, Kaempferia, Cienkowskia and Cienkowskiella and the species is optionally selected from Siphonochilus aethiopicus, Siphonochilus natalensis, Kaempferia aethiopica, Kaempferia natalensis, Kaempferia ethelae, Cienkowskia aethiopica and Cienkowskiella aethiopica. The allergic disease is selected from asthma and atopy.