Medical science is just that, medicine that follows the scientific method. (Or at least it's supposed to).

The scientific method is basically testing guesses (sometimes educated ones) and seeing what happens.

There's a whole lot of structure and guidelines, but testing guesses(hypotheses) is where it's at mostly.

The current state of any science is usually "the best theory we have right now, given the data and resources available to us"

Some people hear that and think "look, they're just guessing, why should I listen to them?" and thats absolutely valid.

Where that falls down is that they then go on to assume all guesses are equal and ignore the time and resources that went in to that current scientific best guess.

Is it always correct? no, is it more likely to be beneficial than a random social media post by an influencer with no medical expertise? Generally yes.

sort of trying shit and then are happy it worked

Most professions could be described like this, but when doctors are "trying shit" it is backed up by many years of training and education, and their behavior is scrutinised by professional bodies and so on.

When your local quack is "trying shit" it's just based on the vibe.

"Herbal medicine's been around for thousands of years!" Indeed it has, and then we tested it all, and the stuff that worked became 'medicine'. And the rest of it is just a nice bowl of soup and some potpourri.

From Dara Ó Briain. Also from him:

Chinese medicine, oh, Chinese medicine! "But there are billions of Chinese, Chinese medicine must be working." Here's the skinny on Chinese medicine. A hundred years ago the average life expectancy in China was 30. The life expectancy in China at the moment is 73. And it's not feckin' tiger penis that turned it around for the Chinese. Didn't do much for the tiger, if you don't mind me pointing out.

Usually herbs found by ethnographers.

Aspirin, for example, IIRC discovered by a scientist investigating traditional therapeutics (tree bark)

I think it depends how you frame this question. For example, aspirin originated from a compound in willow bark. Currently, most of us aren’t chewing on willow bark to relieve pain, but at some point that (or making willow bark teas, etc.) was the case. Whether you consider that as “alternative” depends on what point in history you ask that question.

Leeches, which are still used today, also come to mind. Modern medicine has greatly refined how they’re used, but that’s not how it started.

There are quite a few things that people noticed produced effects but didn’t understand the mechanism. Science changed that.

However, if you consider using things with known properties in a wildly irresponsible manner as the definition of “alternative medicine,” that’s a very different question.

Even when novel therapies from existing medicine do come to light at times, generally this is through scientific observation and testing, not Cletus taking horse medicine.

Aspirin.

Was a tincture or tea of white willow used as a folk medicine for generations until it got studied and the compound in it isolated by Bayer

Cocaine.

Indigenous population would chew coca leaves as a stimulant for various reasons and someone figured found out about it, studied it, and found out how to isolate the active compound and now we have Cocaine

Opiates

Opium Poppy was used for centuries for a variety of uses, but mostly recreational in the form of opium, then it got studied and turned into some of the most effective painkillers we have. (Morphine, codeine, heroin are naturally derived opium compounds, some others are synthetic or a blend such as oxycodone, methadone, fentanyl, carfentanyl)

Edit: white birch bark(I'm not 100% certain this is the right tree, but it was a tree, please correct me if I'm wrong) found the correction in another comment

I was also going to use aspirin as an example, there is also psychedelics as a treatment for various psychological ailments.

I'm also going to post a response i made to a comment further up.

I need to be more specific in how I mean “alternative” here.

What I mean is “not of the current scientific consensus” , which I realise isn’t exactly the same wording as the wikipedia definition

Thats my bad.

I also failed to mention that it also works the other way as well, where current science is discredited(fully or partially) , due to flaws in it’s methodology, reproducibility or some other reason.

In generalities i was thinking more of how certain branches or offshoots of what was considered to be mainstream ( or mainstream adjacent ) science were later found to be scientifically provable.

An example of this is microbes.

They were posited over the years in varied forms by multiple independent people, but they weren't really fully accepted until the invention of a way of actually observing them.

This is largely what medicine was prior to the current , formal scientific method. Local "medicine people" would have salves, cures, potions and other such concoctions passed down to apprentices, they might have some knowledge of how it works, but most of that knowledge would be in the practical application and treatment using said concoctions.

That's not to dismiss this practice, the years of experience and experimentation (of a kind) was, in some cases, essentially a precursor to modern scientific method.

There are ways of analysing effects and positing theories without fully understanding how the underlying mechanism works.

Sometimes that leads to legitimate data around the effects of a medicine or treatment being dismissed as "alternative", at least until formal experimentation is done and verified

As i said in another reply, I'm not saying it's common, all i was saying was that it's a possibility.

Agreed,

I was positing the possibility of a move from "alternative" to "scientifically recognised", not that it was likely to happen.