If you still buy into the myth that potheads are mellow, live and let live types, try suggesting that weed might not be the next penicillin. To paraphrase an old saying, hell hath no fury like a stoner scorned.

Oppose legalization of marijuana and, if you’re lucky, the worst they’ll call you is a “prohibitionist.”

But if historical Prohibition has taught us anything it’s that once a drug is legal, it’s over. Even if legalization proves to be an utter disaster, you’re stuck with it. You can’t go back and make it illegal again.

So we should think long and hard before legalizing another substance that has one purpose and one purpose only: intoxication.

Few things draw people out of the woodwork faster than an attack on their drug of choice. We saw it with cigarette smokers in the 1960s.

Tobacco smoking became common just after the Civil War and for the next 100 years its popularity grew. Not only was it generally believed to be harmless but many people, including some doctors, publicly touted tobacco’s “health benefits.”

Is any of this starting to sound familiar yet?

Then scientists did their research and in 1964 the Surgeon General’s report was issued, stating that smoking caused cancer and other diseases. Cigarette smokers immediately went into denial, defending their drug of choice and, aided and encouraged by Big Tobacco, attacked the research.

But the studies mounted until today the heath damage caused by tobacco smoking is undisputed.

And now, pot advocates want to legalize another plant-based drug whose principal method of administration is to inhale it into the lungs.

What could possibly go wrong?

Weedheads insist that there is no such thing as marijuana dependence. That flies in the face of my own personal experience and observation.

Stoners also claim that you can’t OD on weed. “There are, like, no documented overdoses, dude,” they say. (Stoners say “dude” a lot.) If you define a “documented overdose” as a death caused directly by the chemical THC, those are admittedly rare.

But is death the only harm worth preventing? Ask an ER nurse if she’s ever treated someone in the throes of a pot-induced panic attack? Is that not an “overdose?”

How many car wrecks have been caused by drivers stoned out of their minds who passed blood alcohol tests because they haven’t been drinking?

I would argue that there have been numerous deaths and injuries in automobile and industrial accidents caused by marijuana intoxication. The problem with documenting those is that THC can remain in the system for weeks after the last use, so it is hard to prove CURRENT levels of marijuana intoxication in the wake of an accident.

And what message are we sending kids by legalizing marijuana? Let’s look at a timeline.

• In 2011, 61 percent of Wakefield High School students believed that regular use of marijuana was harmful, according to that year’s Youth Risk Behavior Survey.

• In 2012, voters across Massachusetts (including Wakefield) approved medical marijuana, effectively saying that marijuana is medicine.

• Activists then ramped up their campaign to legalize recreational pot.

• In the 2014 Youth Risk Behavior Survey, only 43 percent of WHS students viewed marijuana as harmful.

We’ve been sending the message that using marijuana is just dandy. And as the surveys reflect, kids are receiving that message — loud and clear.

Public health data shows that when perception of risk decreases, use increases.

Tobacco is an example of the inverse of that. Through decades of anti-tobacco education, tobacco use rates have plummeted, especially among youth. It has taken 50 years of relentless education to get tobacco use, especially among young people, down to the levels where it is now socially unacceptable to smoke cigarettes. Kids think cigarette smoking is “gross.”

Pot aficionados argue that there are many times more deaths associated with alcohol and tobacco use than all other drugs combined. True, but that begs the question: What is different about alcohol and tobacco? Are they many times more dangerous than heroin, cocaine and amphetamine?

Not at all. If anything, alcohol and tobacco are far less dangerous. The difference is that alcohol and tobacco are legal.

So, with all the problems we currently have with alcohol and tobacco, is the logical solution to add yet another legal, mind-altering drug to the mix?

Oh, and that tax windfall that weed activists keep touting as a reason to legalize the bud in Massachusetts? Guess what? They said the same thing in Colorado but revenue fell far short of expectations. The tax revenue generated barely covers the cost of regulating the pot “industry.”

And here comes the news that Colorado voters who legalized pot in 2012 are having second thoughts. A recent poll revealed that fully half of Colorado voters now regret the decision to legalize marijuana for recreational use.

Dopers delight in reminding me that I’m in the minority on this issue. I’m well aware of that. Hey, everyone can’t be as bold and edgy as those taking the majority position.

I don’t doubt that Massachusetts voters will legalize recreational marijuana in 2016. I also have no doubt that, like Colorado voters, they will come to rue the day.

But by then, it will be too late.

Published in the June 18, 2015 edition