New York’s famous 42nd Street will offer natives and visitors a new sight later this week: a mammoth, six-story billboard with a striking message: “Warning—Obamacare may be hazardous to your health.”

It’s part of The Heritage Foundation’s continuing public education campaign to inform the American people about the dangerous side-effects of this unfair, unaffordable and unworkable law, and how it can be stopped.

How will ObamaCare—a 2,700-page law passed by a single vote over bipartisan opposition— harm Americans’ health?

Well, here are five of its worst side effects.

First, many Americans will lose their current health coverage. That’s what’s happening to Rod Coons and Florence Peace, a married couple in Indianapolis. Rod and Florence like their current plan.

“I’d prefer to stay with our current plan because it meets our needs,” Rod says.

Unfortunately, their current coverage fails to meet new requirements imposed under ObamaCare by federal bureaucrats. At the end of this year, that plan will no longer be available to Rod and Florence. They’ll have to find another, ObamaCare-sanctioned plan that may restrict their access to certain treatments or force them to buy coverages they neither want nor need.

Second, many Americans will lose access to physicians they trust. The Wall Street Journal recently highlighted the case of John Nowak, who faces a dilemma when he chooses an insurance plan on ObamaCare’s Exchanges this fall. He “will be able to pick a [revised, ObamaCare-compliant] plan from his current insurer—or go for one that includes his primary-care doctor.”

To save costs, many plans on ObamaCare’s Exchanges are limiting physician networks. So if John chooses to keep his current insurance carrier, he may not be able to keep his current doctor. At minimum, he will pay a lot more to see that physician out-of-network.

Third, ObamaCare places bureaucrats between doctors and patients. The law imposes new penalties on doctors who do “not satisfactorily submit data” that meet Washington bureaucrats’ standards.

It also creates a panel of unelected, unaccountable bureaucrats empowered to make rulings that reduce Medicare spending.

Little wonder that nearly three in five physicians responding to a recent Deloitte survey think the practice of medicine is in jeopardy.

Fourth, ObamaCare dumps millions of patients onto Medicaid—a health program so bad that not even Medicaid patients call it “real insurance.” An analyst for the liberal Consumers Union once admitted that a Medicaid card is but a “hunting license”—“a chance to go try and find a doctor” that actually accepts Medicaid patients.

Moreover, several studies have shown that people enrolled in Medicaid often have worse medical outcomes than those with no health insurance at all.

Expanding a broken Medicaid program is just giving millions of Americans a cruel and empty promise—an insurance card with limited access to real health care.

Fifth, ObamaCare’s reductions in Medicare spending could undermine the health system for millions of seniors.

According to the non-partisan Medicare actuary, the law’s arbitrary spending reductions could cause 15% of hospitals to become unprofitable by 2019, and as many as 40% of hospitals to become unprofitable in the long term. These hospitals could face the choice between shutting out seniors or shutting their doors for good.

Either outcome is unacceptable.

ObamaCare is not just bad for Americans’ physical health—it’s bad for America’s fiscal health as well. If Congress does not act, on January 1, 2014, Washington will tap a gusher of new federal spending on ObamaCare.

Over the next decade, the cost of the law’s new entitlements will soar more than fivefold, from $48 billion in 2014 to $250 billion in 2023.

That will create a lot of pain in taxpayers’ wallets.

For all these reasons and more, Congress must act, and act now, to stop ObamaCare before it takes root.

This fall, Congress will have an opportunity to use its “power of the purse” to block ObamaCare from going forward.

I recently traveled across the country on a town hall tour sponsored by our sister organization, Heritage Action for America.

I met many Americans concerned about the impact of ObamaCare on their health care, who want the law stopped immediately.

There are things we can and should do to improve America’s health care system and reduce costs, but first we must stop ObamaCare before it starts.

The law is a dangerous prescription for America, and its side effects will damage our collective health.

- Former South Carolina Senator Jim DeMint is president of the Heritage Foundation.