What’s the libertarian answer to the combination of false advertising and addictive substances?

There are many products that are specifically targeted to human psychology and made as addictive as possible, like drugs that permanently rewire your brain, a short video platform with neural networks designed to maximise retention, or a highly optimised gambling game with well-timed payoffs to keep the player coming back for more. I'm already sceptical of a lack of regulation in these areas, where a single moment of curiosity can lead to someone bankrupting or killing themselves chasing the next high.

But even ignoring that, what's the non-government solution to addictive substances pedalled through false advertising?

What would you do about a brand of cookies that mixes in addictive drugs to their secret recipe? Now the people getting hooked don't even have to consent once, they can be tricked into an addiction that warps their neurochemistry permanently. Couldn't an already established company that with a large budget then further reinforce the safety of the cookies through marketing, or paying off experts in the field, or a grassroots disinformation campaign?

What about a media juggernaut with highly addictive/radicalising content that engages in a widespread disinformation campaign to try and suppress the truth of the situation? Any reporting of the issue or complaints levied are drowned out by constant waves of "fact-checking" on the news and if not disproving the claims, they at least sow enough confusion to prevent much from being done about it

What if a pharmaceutical company that sold cough medicine marked down 0.01% of some wealthy customers on a special list, replacing theirs and only their medicine with opium, with the people around them none the wiser about the root cause of their recent financial woes, because it certainly couldn't be the helpful cough medicine they themselves take all the time

I'm concerned that these problems can't be fixed by decentralised groups driven by profit, as where's the profit motive for overcoming such powerful competitors with huge revenue streams to discredit any attempt to uncover the truth – possibly to the point that an investigator's brand is ruined and their livelihoods destroyed. Additionally, without seeing the big picture effect, these problems might not even be noticeable by most people – those not directly impacted by it.

On the other hand, a democratically elected government can and does regulate these industries. Being able to look at the bigger picture and see the impact an industry can have on a large-scale, they can see the actual impacts of the situation. There's also a non-profit incentive – lower living standards don't make for good election results. That's why governments regulate casinos and ban hard drugs. What's the non-government solution?