A magazine ad for the testosterone drug AndroGel shows a discount card that allows consumers to pay “as little as $10 per month” for the medicine. Drugmaker GlaxoSmithKline announces in another magazine that it offers discount coupons for the popular inhaler Advair. And a TV commercial for Nexium notes that if consumers can’t afford the heartburn drug, its manufacturer, AstraZeneca, “may be able to help.”

In the past few years, coupons and discount cards have become nearly ubiquitous for prescription drugs. Such incentives are available for 395 medications, according to a recent report from industry consultant IMS Health. In a similar analysis in 2009, a marketing firm found that only 86 drugs came with coupons.

Drugmakers say the coupons help Americans get the medicine they need. But the insurance industry is concerned that they drive patients toward more expensive brand-name drugs, leaving insurers to cover the full cost, which then gets passed on to consumers in the form of higher premiums.

“An individual patient who receives a coupon might not realize that, although that particular prescription may cost less that month, overall what it does is to raise costs for everyone, including themselves,” said Susan Pisano, a spokeswoman for the industry trade group America’s Health Insurance Plans.

For people using Medicare, Medicaid, veterans benefits or any other federal health insurance program, using a coupon or a discount card to buy prescription medication works against efforts to keep federal spending down and may also be counter to federal law, according to some experts’ interpretation.

Prescription drug coupons represent the latest battle in an escalating war between health insurers and the pharmaceutical industry.

Insurers set high co-pays for brand-name drugs to steer their members to less-expensive generics. In response, companies such as Merck, AstraZeneca, Pfizer and many others issue coupons or discount cards that cover that co-pay.

A recent article in the Journal of the American Medical Association outlined the dramatic effect coupons can have on prices paid by consumers. Using cholesterol-lowering drugs as an example, researchers found that the popular statin Lipitor comes with an average co-pay of $30 a month, compared with a $10-a-month co-pay for simvastatin, a generic drug also used to treat high cholesterol. But with a coupon from Pfizer, the drug’s manufacturer, the co-pay for Lipitor goes down to $4 a month, making it less expensive for the consumer than simvastatin.

It’s a great deal for the patient but not the insurer. According to the JAMA article, the insurer pays $18 a month for simvastatin and $137 a month for Lipitor.

The coupons are “designed to get patients to bang down their doctor’s door and say, ‘Give me the most expensive drug,’ ” said Mark Merritt, president of the Pharmaceutical Care Management Association. Merritt’s trade group represents companies that manage prescription benefit plans for private insurance companies and firms that participate in Part D, Medicare’s drug program.