There are ways to save on the cost of prescription drugs for long-term use.

Ordering a 90-day supply of a medication through the mail can save up to 33% on your co-pay.  While you'll pay one co-pay to get a 30-day supply from your local pharmacy, a 90-day supply through mail order usually costs between two and 2-1/2 times your co-pay.

For instance, a 90-day supply of a generic drug with a $10 co-pay would typically cost you $30 in-store (that's for three 30-day supplies).  But you could get one 90-day supply through the mail for $20 to $25.  For a brand-name drug with a $35 co-pay, you'd pay $105 for a 90-day supply in-store, compared with $70 to $87.50 via mail.

Only drugs for long-term use --birth control and those to treat chronic conditions like diabetes, high blood pressure and high cholesterol--qualify for mail-order service through providers such as CVS/Caremark, Medco, and Express Scripts.

For people without prescription-drug coverage, some pharmacies offer discounts.  You can get a 90-day supply of hundreds of generic drugs for $10 at Wal-Mart, $11.99 at CVS (plus a $15 annual fee) and $12 at Walgreens (plus a $20 annual fee for an individual or $35 for a family).  Walgreens also has discounts on brand-name drugs.