No, it is not dangerous to take expired Lunesta"”assuming you have stored it properly. Proper storage means that your prescription has been kept in a cool and dry place (not
the bathroom medicine cabinet). When stored appropriately, most drugs are safe well beyond the expiration date. You may find that your pills are not as potent as they used to be, though. It may help to combine your Lunesta with a soothing bedtime ritual, such as drinking a cup of warm milk.
In general, drugs at risk of going bad soon after their expiration dates include injectibles (such as insulin), liquid drops (such as for the eyes or other non-skin membranes) and chemotherapy drugs for cancer treatment. You should never take tablets or capsules if they are discolored or if there is a change in odor, color or texture. Toss them and get a refill.
If you would like to learn more about prescriptions and expiration dates, read this article by Dr. Thomas Kramer. Dr. Kramer gives insight into the development of expiration dating of medications and reports on a joint study between the U.S. military medical system and the Food and Drug Administration (FDA) to check the stability and safety of more than 100 medications that had been stockpiled in preparation for war and mass deployments. The study found that, even after as long as 15 years past the expiration date, the overwhelming majority of drugs were still safe and effective. I had the privilege of contributing to this study during my time in the West Virginia Air National Guard.