Can You Test Positive for Drugs After Visiting an Emergency Dentist?

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I’m wondering if emergency dental treatment can ever result in a positive drug test. I’m a small-business owner and have a handful of employees. We have a zero-tolerance drug policy, but I’ve never had to enforce it. In fact, I’ve never even asked any of my employees to take a test. However, one of my long-term employees started behaving oddly recently. He’s been calling in sick and not really “there” when he’s at work. His moods are all over the place. Yesterday, he called in sick again and it’s his third absence this week. This has been festering for a few months now, so without thinking, I told him he needed to take a drug test before returning to work. That’s when he told me that he’s been missing work for a toothache and had just gone in to have a root canal done on a tooth today, and that because of the anesthetic the dentist used, his test will not come back clean.

This puts me in a tough spot. Is this even true? I remember hearing murmurings of dental anesthetics having the same roots as cocaine and, if he received pain medication, it would show up on a test as heroin, right? Is there any way we can tell the difference between whether this person has a drug problem or if he’s testing positive for something related to the dental visit? If not, how long do we have to wait to test him?

For what it’s worth, he’s been a really great employee. He’s like family to me. I’m really torn here. I don’t want to be accusatory or keep him from work because I know he needs the money, but at the same time, I’m worried about his health and concerned he could be a liability for my company.

Thank you,


Dear Peter,

This is a tough spot to be in. First and foremost, if you have questions or concerns related to employment law or you have a feeling this could result in a legal issue for you, talk to a business law specialist. This page will go over your concerns, but you’ll ultimately have to make the decision you feel is right.

Dental Anesthetics Are NOT Derived from Cocaine

It’s a common misconception that dental anesthetics have commonalities with cocaine because the names sound similar, but they do not. They’re different substances and the body processes them in different ways. Your employee will not test positive for cocaine after having any common dental anesthetic. Of course, it could be that he’s clean and genuinely believes the myth or it could be that he’s not clean and is trying to cover his tracks. There’s only one person who knows which is true.

Some Medications Prescribed by Dentists Can Create “False Positives”

That said, some medications commonly prescribed during a dental emergency could result in a false positive. In terms of cocaine, there’s only one medication which is associated with false positives: amoxicillin. Some studies have produced false positives, while others conclude it does not create false positives. Once you get into pain medications or sedation medications, it’s a bit different. Quite a few can register as various substances, such as opiates and amphetamines, but it also depends on the medication and the type of test being administered. Oftentimes, labs can confirm whether something was a false positive by running an alternate test.

Speak with a Lab in Your Area About Proper Testing

While there are over-the-counter drug tests, this is probably one time where you really need a professional involved. There are many labs which specialize in employment drug screenings. If they have the specifics of the situation and know which medications your employee was given or prescribed, they can run the right tests to give you the answers you need and will let you know if there’s any room for error.

Check with NIH for Advice on Helping Your Employee

The National Institute on Drug Abuse has a fantastic resource called “What to Do If Your Adult Friend or Loved One Has a Problem with Drugs.” It can be a real challenge when you’re the boss and also a friend, but if he is struggling with addiction, having someone in his corner may help. Best of luck to the both of you.

This blog is sponsored by Elgin emergency dentist, Dr. Steve Sirin.

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