If you’re getting drug tested and you’re worried that you may not pass it, you might start wondering how long the drugs are actually going to stay in your system. Are they going to show up on that test?

There are many factors to consider here, such as your age, height, weight and metabolism. Naturally, the type of drug used is also critical. The type of test administered — there are urine tests, blood tests and hair tests, just to name a few — makes a difference in the results, as well.

One more thing to consider is the frequency you use a drug. If you are a chronic user, you can expect some drugs to stay in your system for a lot longer than if it was just a one-time event.

For instance, maybe you used phencyclidine, which is often called PCP. It’s a hallucinogen and it is addictive. If you used it once, it could still show up in tests for anywhere from 8 days to 14 days, as a general rule. If you are a chronic user, though, it could appear in tests for around 30 days.

The same thing is true for benzodiazepines like Xanax or Valium. You can use these legally in many cases, but some people still use them illegally or become chronic users. If you just take a therapeutic dose, it typically only remains in your system for three days. If you are a chronic user, however, it can still show up for four weeks to six weeks — or even longer, in some cases.

Having a drug in your system doesn’t necessarily mean you were under its influence at any given point. If you do end up facing drug charges due to a drug test or any other reason, make sure you know all of your legal defense options.