According to the FDA, generic drugs are identical to their more expensive name-brand counterparts. However, if you opt for generics when given a prescription by your doctor, you could be doing serious unnecessary harm to your wallet if you don’t shop around at a few pharmacies first, according to a new study.

The study, conducted by Consumer Reports, looked at the cost of a one-month supply of five different popular drugs at over 200 pharmacies across the country. All of the drugs involved in the study had only recently gone generic. Shockingly, the researchers found that the lowest-priced pharmacies were about 447% cheaper than the most expensive pharmacies. Lisa Gill, who regularly covers prescription drugs for Consumer Reports, said that “irrational pricing” is common in the immediate wake of a prescription drug going generic.

5 Popular Generic Drugs

In conducting their study, Consumer Reports researchers looked at the prices of five drugs that recently had generic versions released. The name-brand versions of these drugs are as follows:

• Singulair, for asthma
• Lipitor, for high cholesterol
• Lexapro, for depression
• Actos, for diabetes
• Plavix, a blood thinner

The researchers shopped at every type of pharmacy you could imagine, including small independent operations, grocery stores, online pharmacies like FamilyMeds.com and HealthWarehouse.com, national franchises like Walgreens and CVS, and finally supermassive retailers like Walmart and Costco.

Incredible Differences in Prices

If you’re looking for the lowest generic drug prices around, you’d be wise to shop at Costco, according to the Consumer Reports study. Although you might think that the cost of a Costco membership would offset some of the savings, anyone – including non-members – can utilize the Costco pharmacy.

On the opposite end of the major-chain spectrum were Target, Rite Aid and CVS, which offered the highest prices on generic prescription drugs among national retailers. Online pharmacies usually offered some of the lowest prices, but they were middle-of-the-road for certain drugs, too. Prices at smaller independent drug stores varied enormously, but were generally higher in urban areas than rural ones.

Just for example, a one-month supply of generic Singulair was priced at:

• $27 at Costco
• $29 at FamilyMeds.com and HealthWarehouse.com
• $57 at Walmart
• $165 at CVS
• Between $10 and $193 at grocery stores and independent pharmacies

As you can see, Costco isn’t unbeatable when it comes to generic prescription drug prices. In fact, Costco charges $101 for a month’s worth of Actos, while it can be found for as little as $37 at a rural independent pharmacy.

How to Save Money on Generic Prescription Drugs

These wild differences in generic prescription drug prices usually only apply to drugs that are newly available as generics. Once the generic version of a name-brand drug is available for about a year, the prices generally stabilize to about 10% of what you’d pay for the name-brand version, according to Consumer Reports. However, you can still save up to hundreds of dollars each month, especially if you have multiple prescriptions, by shopping around. Consumer Reports offers the following tips for saving money:

• Head to a rural pharmacy when you buy your generics. If this requires a significant drive, fill all your prescriptions for the month in one trip.
• Ask for lower prices. Even if the pharmacy doesn’t offer senior or student discounts, they may be able to lower their prices upon request, especially if you’re paying without insurance.
• Ask whether the store has a loyalty program. You might get a bulk discount by purchasing generic drugs from the same pharmacy regularly.
• Compare the price against your co-pay. You might find that it’s cheaper to just pay for the drug outright rather than getting your insurance company involved.
• Ask for a longer supply. You might save 20% or more by purchasing a 90-day refill rather than a 30-day refill from the same store.

The Bottom Line

Prices on generic drugs can vary enormously from one pharmacy to the next, especially during the first year after a name-brand drug goes generic. According to a study by Consumer Reports, Costco is the most inexpensive national retailer when it comes to prescription generic drugs. However, you may find even lower prices by shopping at independent pharmacies in rural areas.