Lydia Folger Fowler was born in Nantucket, Massachusetts, to a family descended from the first settlers of the island. She was related to Benjamin Franklin, Lucretia Coffin Mott, and Maria Mitchell. She attended the Wheaton Female Seminary in Norton, Massachusetts and began teaching there at the age of 20. In 1844, she married Lorenzo Niles Fowler, a phrenologist, with whom she had three daughters. She became a public lecturer and writer on anatomy, hygiene, and physiology. With her husband, she traveled around the country, speaking mainly to audiences of women on the subjects of child care and hygiene. The family publishing house of Fowler and Wells published three of her books: Familiar Lessons on Physiology (1847),
Familiar Lessons on Phrenology (1847), and Familiar Lessons on Astronomy (1848). She decided she wanted to become a physician, but no medical schools in the USA admitted women in that era. In 1849, she enrolled in the Central Medical College in Syracuse, New York, an unrecognized "eclectic medicine" school, one of eight women entering the first co-ed class. When she graduated, she was only the second woman in the USA to earn a medical degree, following Elizabeth Blackwell. She practiced medicine in New York City from 1852 to 1860. She then joined the faculty of her medical school, now known as Rochester Eclectic Medical College, becoming the first woman professor in an American medical school. She was active in women's rights organizations, and participated in the 1848 Seneca Falls Convention. Elizabeth Cady Stanton later dedicated her massive work The History of Woman Suffrage (1881) to her. In 1863, she and her husband moved to London, where she became active in the British Women's Temperance Society. She wrote prolifically, brought medical care to poor women in the slums of London and Ireland, and continued teaching women about health and child care. Books and treatises written at this time included How, When, and Where to Sleep; The Brain and Nervous System: How to Secure their Healthy Action; The Eye and Ear, and How to Preserve Them; and How to Secure a Healthy Spine and Vigorous Muscles (1864).