Have you ever tossed an expensive bottle of prescription or over-the-counter drugs because they had “expired”? A class action lawsuit claims these dates are basically bogus, made up to goose replacement sales by drug makers who know the drugs are good for years, even decades, after the “use by” date.

The class action suit, filed in Missouri, accuses Pfizer, Bayer, and Johnson & Johnson of using “unconscionable, unfair, deceptive, unethical and illegal” methods to get consumers to throw away their products when expiration date has passed, though the companies know “that if stored properly these medications can and do remain chemically stable, safe and effective long after those dates.”

How do they know the meds are safe? Studies conducted by major medical research organizations and the Food and Drug Administration have found that 90% of more than 100 drugs, both prescription and over-the-counter, were perfectly good to use even 15 years after the expiration date.

Advice from Harvard Medical School: The next time you face the drug expiration date dilemma for a minor condition, it’s probably fine. If the expiration date passed a few years ago and it’s important that your drug is absolutely 100% effective, you might want to consider buying a new bottle. And if you have any questions about the safety or effectiveness of any drug, ask your pharmacist.