Medicines are sometimes withdrawn from the market after having been used therapeutically. When that happens it is usually because of some adverse effects or adverse reactions that they have caused. Over the years the delay between marketing and withdrawal in such cases has fallen dramatically. One of the longest delays between the first clinical use of a compound and its withdrawal from the market was that experienced by chloroform, which was first used clinically in 1847 and, although it was known to have caused many deaths and was eventually superseded by better compounds, it was not withdrawn anywhere until 1976 and in the UK until 1979.
There are several possible courses of action that regulators and/or manufacturers can take when a new adverse drug effect is observed or a new adverse drug reaction is experienced. They can simply add a warning to the product label about the possible adverse outcome, or they can add a new caution or contraindication, issue a specific warning to doc