Ask the MRO

Frequently Asked Questions


I am not taking any prescription drugs and I don’t use illegal drugs. How could I have methamphetamine in my urine?

Methamphetamines can be present in the urine after use of the Vicks Inhaler. The amphetamines occur in two forms (isomers), the l- or legal form and the d- or drug (usually illicit) form. After Vicks Inhaler use the predominant form in the urine is the l- form. Additional testing by the laboratory will show whether the Vicks Inhaler excuse is valid. For the Vicks Inhaler to be a valid excuse the l- form should account for 80% or more of the isomers.

I am taking a medication obtained in another country. Might this explain my amphetamine positive test?

Foreign medications, especially certain Mexican diet pills, are known to cause positive urine tests for amphetamines and methamphetamines. When a prescription is available to document the legitimate use of the medication the MRO will call the test negative. However safety concerns may still exist if the donor is in a safety-sensitive position.

Do I, as the employer, have to obtain the information from previous employers before I can use the individual to perform safety sensitive functions?

No. You may permit the individual to perform safety sensitive functions for 30 days while you await this information. However, ideally, you should obtain this information before the individual first performs a safety sensitive function.

What happens if I don't receive the information from the previous employer within 30 days?

You cannot permit the employee to perform safety functions after 30 days, unless you have made and documented a good faith effort to obtain the information.

What happens if I find out that the applicant/employee did have a DOT violation with a previous employer?

You must not permit the individual to perform a safety sensitive function unless the individual can document that he/she was evaluated by a Substance Abuse Professional (SAP) and successfully completed the DOT return to duty requirements.

Can FirstLab conduct these Drug and Alcohol Background Checks for me?

Yes. FirstLab has dedicated a team of employees who are trained to conduct the required drug and alcohol background check in accordance with the DOT regulations. We guarantee that you will receive a complete report within the required 30-day time limit.


Cocaine use, in both the powdered and crack form, has had a significant adverse impact on American society. Cocaine abuse has decreased in recent years, however it is still the second commonest drug found in urine drug testing.

I don't do drugs. Certainly not cocaine. How can any drugs show up in my urine?

As with marijuana most cocaine users will deny use. However, again there are some individuals, who are around cocaine, don't knowingly use the cocaine but still test positive at work for cocaine. Clearly a drink can be spiked with cocaine or cocaine can be sprinkled on food. While this may be a reasonable explanation for the positive test it is not a legitimate medical explanation because illicit cocaine use by the donor can't be ruled out.

My dentist used novocaine during a recent visit. Could this explain the cocaine in my urine?

Cocaine is infrequently used in certain dental, eye, ear and throat procedures and can be easily verified by the MRO. The topical analgesics ending in "caine" such as tetracaine, benzocaine, lidocaine and novocaine are not structurally related to cocaine and do not explain the cocaine or the metabolite, benzoylecgonine, in the urine.


Within the drug class of opiates testing pro-grams focus on codeine, morphine and a specific heroin metabolite, 6-monoacetylmorphine (6-AM). Codeine metabolizes to morphine so urine drug tests after codeine use may show codeine alone, codeine with morphine or morphine alone. Heroin can't easily be tested for by the laboratory but heroin does metabolize to 6-AM and then morphine. Therefore after heroin use the urine will probably show morphine and on rare occasions 6-AM. Morphine use will show morphine in the urine.

Opiates have been of great importance for pain relief but the mood changes (i.e., euphoria) associated with drug use have also led to epidemics of abuse. Heroin abuse is again on the increase and since it is now available in a non-injectable form, users do not have the fear of HIV infection from needles.

As stated in the introduction most opiate positive urine tests are called negative by the MRO either because there is a valid prescription medication that explains the result, there is no clinical evidence of abuse such as needle marks, or poppy seed use explains the result (poppy seeds contain morphine).

I used my "spouse's" Tylenol with codeine. Does this explain my positive test for morphine?

While the Tylenol with codeine would explain the morphine in the urine, another problem exists. It is illegal to use someone else's prescription for Tylenol with codeine. So if the donor admits to use of a spousal medication that contains an opiate then the MRO must report the result as a positive because of unauthorized use.


Few questions arise with phencyclidine (PCP) positives. There is currently no medical application for PCP in the United States although in Europe the drug is still used as an anesthetic. PCP use causes unpredictable effects ranging from psychosis to fits of agitation and excitability. These severe effects have even given PCP a bad reputation among drug users.

I haven't used PCP for weeks. How could it show up in my urine?

PCP is similar to marijuana in that after chronic use PCP may be excreted into the urine in detectable amounts for several weeks after the last dose.