PURPOSE: A composition containing 5alpha-reductase inhibitors and minoxidil is provided to prevent hair loss and promote hair growth. CONSTITUTION: An external use composition for preventing hair loss and promoting hair growth contains 5alpha-reductase inhibitor, and minoxidil, or pharmacologically acceptable salts thereof. The daily dose of the 5-alpha reductase inhibitor applied by transdermal administration is 0.8 ug to 0.12 mg. The daily dose of minoxidil or pharmacologically acceptable salt thereof is 0.008g to 0.12g. The 5alpha-reductase inhibitor is finasteride, pharmacologically acceptable salt thereof, dutasteride, or pharmacologically acceptable salt thereof. The external use composition additionally contains alphatradiol. The external use composition further contains low molecular mono alcohol of 1-4 carbon atoms, polyvalent alcohol；, and water.본 발명은 5α-리덕타아제 억제제 및 미녹시딜을 포함하는 탈모방지 및 발모촉진용 외용제 조성물에 관한 것이다. 본 발명의 탈모방지 및 발모촉진용 외용제 조성물은 종래의 경구용 5α-리덕타아제 억제제 및 미녹시딜을 각각 단독으로 또는 병합하여 사용할 때보다 훨씬 적은 양의 약물을 사용하면서도 동등 이상의 우수한 탈모방지 및 모발성장촉진 효과를 제공한다.
