The invention provides application of a pharmaceutical composition to preparation of an external
medicine for treating
allergic contact dermatitis, wherein the pharmaceutical composition is prepared from the following
raw material medicines in parts by weight: 25-35 parts of purslane, 25-35 parts of fructus cnidii, 15-25 parts of fructus kochiae, 15-25 parts of nidus vespae, 5-15 parts of cortex dictamni, 5-15 parts of pepper, 10-20 parts of
rheum officinale and 10-20 parts of
senecio scandens. The invention also provides a preparation method of the pharmaceutical composition. The composition has the effects of clearing heat and
drying dampness, cooling blood and diminishing swelling, and dispelling wind and arresting
itching, is externally washed on an affected part, effective components directly reach the affected part after being absorbed by
skin, has the characteristics of direct action, quick response, convenience and simplicity, small toxic and side effects and the like, has the effects of clearing heat and
drying dampness, cooling blood and diminishing swelling, and dispelling wind and arresting
itching together, and has a remarkable effect on treating the
allergic contact dermatitis.