Can prescription drugs lead to a failed drug test?

Can you fail a drug testing because of drugs you’ve been prescribed?

People are prescribed drugs by their doctor every day, whether it’s for a short term ailment or for a longer-term issue. It’s so common that many people don’t give it a second thought, but when this happens to you in the future, remember to ask your doctor some questions to ensure you won’t get caught up in drug testing on the roads or at work.

An Australian Government website called Health Direct tackles this very issue and makes it quite clear that if a drug has the capability of effecting your driving, it could very well land you in trouble if you’re asked to provide a drug test on a roadside.

“Some medicines have side effects that can affect your driving. Like drink driving, it is illegal to drive under the influence of drugs, whether they are legal or illegal,” says the website. Of course, the same can be said about working when taking these medications.

This is pretty much commonsense as some prescribed drugs are very similar to illegal drugs in the way they work. Codeine, morphine and fentanyl, for example are all opioids and come from the same family of drugs as heroin, so the need to take care while taking drugs like these is paramount. The obvious difference, of course, is that when taking prescribed drugs the quantity and quality of the drug being taken is known, while when taking an illegal drug it isn’t.

But that doesn’t mean prescribed drugs can’t land you in trouble, particularly if you take them with other drugs, mix them with alcohol or don’t take them as prescribed.

Safety is the concern

The concern about some prescribed medicines is all about safety, because in some cases the side effects can be quite significant. In fact, Health Direct says that, “Some medicines can affect your driving so significantly that they are equivalent to drinking more than the legal limit for alcohol.”

While this is a sobering thought, if you are taking medication and you think it may be affecting your ability to drive or work safety, do simply stop taking it. Stop driving and working and talk to your doctor. There might be other medications you can take which don’t have the same side effects.

Take steps to stay safe and avoid a failed drug test

  1. First and foremost, talk to your doctor if you’ve been prescribed a drug. Ask if there is any potential issue with driving or working while on the drug.
  2. Only take medicine as prescribed. Don’t try to catch up if you’ve forgotten to take a dose, by having doses closer together.
  3. When taking any medicine, if you have symptoms such as feeling drowsy or tired, dizziness, blurred vision, confusion, issues with concentration or anxiety, stop driving and stop working, but don’t stop taking your medicine without speaking to your doctor first.
  4. Medicines to be careful with include sleeping pills, epilepsy medicine, some antidepressants, antihistamines, and opioids such as codeine and fentanyl for pain relief.
  5. As with any drugs, there are always individual aspects at play. A drug may affect you more than someone else, so listen to your body and look out for symptoms. If in doubt, don’t drive or go to work.


Can you fail a drug testing because of drugs you’ve been prescribed? Credit Highway Patrol Images

By Michael

Michael is the founder of Integrity Sampling and is responsible for overseeing all national operations. He is based at Integrity Sampling's head office in Melbourne and is also responsible for the co-ordination of drug and alcohol testing within Victoria, assisting in the implementation of drug and alcohol (fit for work) policies and the presentation of drug and alcohol education and awareness programs. You can connect with Michael Wheeldon on LinkedIn

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