Medical privacy in US under "matchback" attack

Washington

EVER since the days of castor oil laxatives and mercury syphilis tablets, pharmacists and patients have had a tacit understanding: whatever you buy, the information is confidential.

No longer. Drugmakers and Internet firms are quietly joining forces to link US pharmacy records with online accounts to target ads at people based on their health conditions and the prescription drugs they buy.

In a little-known process, third-party companies assign patients unique numerical codes based on their prescription-drug records - a practice websites also rely on to track their registered users. The two sets of data can be linked without names ever changing hands, allowing pharm…