If someone said,
- “I have taken drugs regularly every day since 2014.”
Does drugs, in this context, mean illegal substances: heroine, opium, marijuana; or the ones, legal, are used in healing and treatment?
It's hard to answer your question without more context, but I'm leaning toward these are illegal drugs.
Typically if you are on multiple legal drugs, you wouldn't refer to them as simply "drugs". You would say "I am taking multiple prescription medications since 2014". If you hear the word "prescription" or "medication" these are nearly always going to be legal drugs.
It could be either, depending on the context.
In common usage, "drugs" more often means illegal, while legal drugs are called "medicine". But that's far from 100%, you really have to look at the context.
I'm reminded of the day my Sunday school teacher told the class, "I'm off the drugs and in rehab now." I commented that he might want to make clear that he meant that, following his surgery, he was no longer taking pain-killers and was now in occupational therapy to build his muscles back up.