Because mail programs usually ship a 90-day supply at a time, they’re ideal for drugs used on an ongoing basis, not those you need immediately or briefly. (ISTOCKPHOTO)

Does having your medication mailed to your door sound appealing? The discounts are often significant, especially for drugs that people take regularly, such as those for diabetes and high blood pressure. You might be able to order a three-month supply for a co-payment of just a few dollars. In some cases, you might be eligible to get generic medications with no co-pay at all, and free shipping. In addition, of course, there’s no need for you to go to a drugstore.

“Convenience is such a driver for people determining whether or not they want to get prescriptions through the mail,” says Lucinda Maine, executive vice president and chief executive of the American Association of Colleges of Pharmacy. “And with the right mail-order service for drugs you take, you can save money.”

Sounds like a great deal, doesn’t it? It certainly can be — but isn’t always. Here are the pluses and minuses:

Not all meds should be mail-ordered. Because mail programs usually ship a 90-day supply at a time, they’re ideal for drugs used on an ongoing basis, not those you need immediately or briefly. And certain drugs, including some for pain and insomnia, have shipping restrictions.

Savings aren’t guaranteed. Before ordering, see what your insurer’s plan will charge for mail-ordering and shipping your meds. Check your local pharmacy’s prices, too; many offer 90-day prescriptions with low co-pays. And chain and big-box stores have many generics at deep discounts. Kmart, Sam’s Club, Walgreens and Walmart, for example, offer a 90-day supply of dozens of generics for only $10, and that usually includes free shipping. (In some cases, there’s an annual membership fee.)

You may have to request generics. Mail-order pharmacies can sometimes be slow to make generics available to customers, though that gap has narrowed. To ensure that you don’t get stuck with a pricier brand-name drug, ask your doctor to prescribe a generic — and to state it clearly on the prescription.

You may need two prescriptions to start. To ensure that you’ll have enough medication while you wait for your insurer to process your new order — which can take up to two weeks — ask your doctor for two prescriptions, one for a 30-day supply to be filled right away at a local pharmacy and one for a 90-day mail-order supply.

You should keep your pharmacists in the loop. It’s best to fill all prescriptions at one pharmacy so your pharmacist can alert you to possible drug interactions, recalls and other important information. If you get maintenance medication via mail order while also receiving drugs you need occasionally at a walk-in pharmacy, let each one know all of the medications you’re taking and update them regularly about any changes.

Automatic refills can be useful, but . . . If you know you’ll be taking a medication at a set dosage for a long time, consider getting automatic refills so you don’t have to renew that prescription every three months. But if you stop taking the drug or your dose changes, you might have to inform the mail-order pharmacy. Otherwise, you might get drugs you don’t need. To avoid that, ask your insurer whether its service will alert you before shipping medication. (Medicare Part D drug plans require mail-order pharmacies to get the okay from a patient or caregiver before shipping a new prescription or refill.)

Timing can be tricky. Medications may not always arrive on time. If you don’t have automatic refills, make sure you set up orders online or over the phone at least two weeks before you’ll run out.

Copyright 2016. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.