When you think of Walgreens or CVS, you probably have a drugstore in mind. But as people seek easier access to care, they are increasingly visiting chain pharmacies for their in-store medical clinics.

Still, this helpful trend can present challenges.

When my wife got sick recently while we were out of state on vacation, we stopped by one of Walgreens' Take Care in-store clinics.

The clinic was a great convenience compared to an emergency-room experience just hours before. My wife, a registered nurse, had an infection, and the antibiotic that her personal physician had prescribed wasn't working. So we went to the emergency room.

After waiting for 11/2 hours, sitting next to people coughing and sneezing, we left. ER staff warned us that she would be charged since she had already signed in and had her vital signs taken.

And, indeed, the bill, which recently arrived, was more than $600! I've since given them our insurance information, so we'll have to see what the final charge is.

At Walgreens, we were charged only $35 for the visit, plus the lab cost for her culture, which was also reasonable. Our insurance may cover part of the bill.

The clinic contracts with an off-site physician who oversees care. They treat minor injuries and illnesses like sore throats and urinary tract infections and are generally open after-hours and on weekends.

We waited only about five minutes before we were seen by a nurse practitioner. We had time to chat, so we asked her about her experience.

I was surprised to learn that, during any downtime, Walgreens expects the nurse practitioners to go out into the store and promote the clinic with people waiting for prescriptions. She said she has refused to do this because she felt it was unprofessional, but still the expectation was there.

When she prescribed the new antibiotic, it was done electronically - and, without asking us, she sent it as a matter of routine to the in-store pharmacy.

When we asked for the prescription, she said immediately, "Oh, did you want it sent somewhere else? . . . I can do that."

Prescriptions from the clinic are probably not a giant source of income for Walgreens. But sending the prescription right to its pharmacy did raise a red flag for me.

With a pharmacy owning the clinic, employing the prescribers, doing the purchasing, and deciding what drugs will be on the clinic formulary, the operation has the opportunity to influence which drugs will be prescribed.

We could see some enterprising owners capitalizing on this for profit.

So this does bear watching.

Cohen is president of the Institute for Safe Medication Practices in Horsham and writes for the Inquirer's "Checkup" blog. He can be reached at mcohen@ismp.org.