Interviews with patients, patient advocates and doctors suggest that specialty pharmacies do not always live up to their billing. There can be onerous refill policies that require hours on the phone, shipments that are delayed or error-ridden, and difficulty reaching a pharmacist or other representatives.

Moreover, many patients are limited to one specialty pharmacy — often one owned by their insurer or pharmacy benefit manager and requiring delivery of drugs by mail. That leaves patients without options if they are dissatisfied.

Consumer Watchdog, a consumer advocate group, has sued four insurance companies over their policies of restricting the pharmacies that patients can use to obtain drugs for H.I.V. Three of the companies — Anthem Blue Cross of California, UnitedHealthcare and Aetna — have since changed their policies to provide more options for H.I.V. patients. The most recent of the lawsuits, against Cigna, was filed in April.

There are also questions of potential conflicts of interest, since many of the bigger specialty pharmacies are owned by insurers or pharmacy benefit managers like CVS and Express Scripts. Pharmacy benefit managers, or P.B.M.s, are supposed to help health plans control drug costs. But will they have the zeal to do that if they are making money dispensing these expensive medicines?

“Forcing people to use a P.B.M.’s own specialty pharmacy creates a situation where the fox is guarding the henhouse,” said David Balto, an antitrust lawyer in Washington. He represents independent specialty pharmacies, some of which claim that insurers and pharmacy benefit managers funnel business to their own pharmacies, even if others may provide better service.

Yet another issue is that some drug companies are choosing only a few specialty pharmacies to handle their products. That could give pharmacies an incentive to position themselves as allies of the manufacturer more than of the patient or health plan.