You shouldn't take painkillers for general soreness after working out

Inflammation causes pain, but it's also the first step towards healing. When you work out you're damaging muscles. In response your body adapts, healing that damage and making you stronger so that you can better handle those forces in the future.

Some research has found that some of the pro-inflammatory compounds produced by exercise then cause the release of powerful anti-inflammatory substances that help damaged muscles heal and have other long-lasting health benefits. There's reason to think that artificially suppressing the initial inflammation could prevent that healing process, neutralizing some of the real benefits of exercise.
  1. Some researchers have found that both ibuprofen and acetaminophen (another type of pain reliever, often branded as Tylenol) suppress the protein formation that occurs in muscles after high-intensity exercise. 
  2. Even more research has found that nonsteroidal anti-inflammatory drugs like ibuprofen (aspirin is also in this category) inhibit bone healing. 
  3. There's even some evidence showing that using ibuprofen regularly for soreness may damage cellular tissue and generally prevent your body from even being able to take full advantage of exercise.
  4. Even using ice baths or ice packs to reduce inflammation can slow the body's adaptation process, though that just delays healing, it doesn't actually stop it from happening.
There's an exception to all this, of course. If you have an actual injury, using a painkiller to reduce inflammation may help you heal. 

But for general muscle soreness, if you want your body to recover best and get stronger, you're better off just toughing it out.