He came to this country in 1716, and settled in Boston in 1718. Although a skilful practitioner, he violently opposed inoculation for the prevention of smallpox, His prejudices were strong, and his language frequently intemperate. He wrote much on medical and political subjects, and proposed "a stamp duty upon all instruments used in law affairs" for revenue, but the suggestion lacked novelty. 

A town in Worcester County, Massachusetts, of which he was the principal owner and benefactor, bears his name. 

His "Summary, or Historical Account of the British Settlements" (1748'53, left incomplete at his death) is inaccurate, and records his private grievances as well as public affairs. 

He printed an almanac (1743'4), entitled " Mereurius Novanglicanus," which is still valued for its chronology. Adam Smith called him "the honest and downright Dr. Douglass." He also wrote treatises on "Smallpox" (1722'30); "3Practical History of a New Eruptive Miliary Fever which Prevailed in Boston in 1735'6" ; and a work on "Midwifery."