Travelers should be very careful when seeking Medical attention in Mazatlan. There are very good hospitals there (Sharps if you have the money, Military downtown if you don't) but there are also clinics that prey on tourists.
Be VERY careful of highly advertized bucket shops that demand your passport, have under-trained personnel because they spend all their money on internet come-ons and hotel zone rents. Be VERY careful of American employees there who try to get your insurance company involved or your credit card. If you are in doubt check with the consulates or the local English language newspaper http://pacificpearl.com