The opposite of preventative is reactive. Reactive approaches to problem-solving are those that are taken after an issue has already occurred. This means that instead of taking proactive steps to prevent a problem from happening, a reactive approach is taken to address the problem after it has already happened. Reactive approaches are often seen as less efficient than preventative approaches, as they often require more time and resources to address the issue. However, reactive approaches can be beneficial in certain situations, such as when a problem is too complex to anticipate or prevent. In these cases, a reactive approach can be used to address the issue quickly and effectively. Ultimately, the decision of whether to use a preventative or reactive approach depends on the situation and the resources available.