Growing up as the child of older (both were over forty when they adopted me; the photo is of me, at three, on the blacktop where I skinned pretty much everything) first generation American parents must have hardwired me for unusual historicals right from the start. Many of the treatments for the minor childhood illnesses or injuries I had in the 1960s/70s were as likely to come from the traditions my mothers and aunts, one of whom who worked as a nurse, learned from their mother, who learned them from her mother back in Italy in the early 20th century.
As a child, I'd often wondered what my mother grew that patch of mint for (aside from the delightful smell) but when puberty hit, I found out it was a natural remedy for menstrual cramps. By then we had moved away from the house with the fresh mint in the garden, so it had to come from a store, but it still worked, and the mint tea also worked to help with nausea.
Sore throats were as likely to be treated with licorice as commercial medications, which may be why I still like licorice today, and I will long remember the discussion my parents had when my father wanted to give me a hot toddy (mostly rum) to help ease the discomfort of a bad case of chicken pox when I was ten. They left it up to me, and I declined.
One of my strongest memories of my mother's Aunt Anna, who I only knew as an elderly woman who spoke a fast stream of Italian was the time when I'd talked a neighbor child into splitting a bar of Ex-Lax (to be fair, I was five and the grownups had described it to me as chocolate.) Being sorely lacking in my Italian, I can't vouch for anything said that day, but Aunt Anna refused to let my mother take me to the doctor, instead pounding an endless supply of ice with a hammer and pouring it down my throat before depositing me in the bathroom with even more tall glasses of ice. When I asked my mother to translate, she said this was Aunt Anna’s treatment for loose bowels, something she learned back in Italy.
Since I survived and turned out okay, my foremothers must have been on to something, so when characters in my historicals now have the need for doctoring, I turn to the state of the art medical care of their time. Often, such as in colonial settlements, the most advanced medical treatments meant calling in whoever had dealt with the illness or injury before. If the need was something the person hadn't encountered before, common sense was often the best guess.
In my colonial historical romance, MY OUTCAST HEART, the hero, Dalby, suffers third degree burns to one hand. Today, witnesses would call 911 and paramedics would rush him to the burn unit, where trained professionals would examine him and use a variety of treatments and procedures to find out how bad the damage was, how much mobility he might be able to retain and even address cosmetic repair. In 1720, Dalby was lucky this occurred in winter, so heroine Tabetha can drag him outside and stick his hand in a snowbank. The cold would help, but the "everybody knows" medicine of the time--likely coating the burn in butter or bear grease--we now know would have the exact opposite effect.
Looking at the folk medicine of the times I write about, and consulting with several friends who work in the medical field of today as well as visiting living history museums lets my characters have the best--or worst--of both worlds, depending on what the story needs. Good thing a great read is excellent medicine in any time.