药学（英语：Pharmacy），是以各种科学为基础来研究药物的知识系统，与药理学（Pharmacology）是不同的概念。药理学主要为生物医学的科学研究，而药学则主要是利用药理学的知识为病人提供更高质素的医药治疗及服务。前者为科研性质，后者为临床性质。另外，药学与药剂学（Pharmaceutics）的概念也经常被混淆。药剂学为药学的一门分支，只专门研究制药的部分，而药学本身则是将各种医药知识化为临床实践。在某些地区（例如香港），中文「药剂学」一词通常是指「药学」（Pharmacy）。

目前药学的含义包括药学科学、药学职业、药房等。

Pharmacy is the science and technique of preparing and dispensing drugs. It is a health profession that links health sciences with chemical sciences and aims to ensure the safe and effective use of pharmaceutical drugs.

The scope of pharmacy practice includes more traditional roles such as compounding and dispensing medications, and it also includes more modern services related to health care, including clinical services, reviewing medications for safety and efficacy, and providing drug information. Pharmacists, therefore, are the experts on drug therapy and are the primary health professionals who optimize use of medication for the benefit of the patients.