Prescription Meds That Cause Positive Urine Tests

Many employers use urine drug screening to test employees or potential employees for the use of drugs that are likely to be abused, including illegal drugs. Several types of controlled substance medications are available with a physician’s prescription that can cause a positive result for a number of urine drug tests. These include pain relievers, stimulant medications and other medications used to manage anxiety.

About Urine Drug Tests

Most employers who routinely do urine drug testing, have a set panel of drugs that are being tested for. Any employer who performs work for government agencies such as federal or state departments of transportation will be required by law to routinely perform pre-employment, random and suspicion based drug testing. Standards have been established by the United States Department of Transportation for a standard five-panel drug screen that routinely tests for cocaine, marijuana (THC), amphetamines, opiates and phencyclidine (PCP). While most employers will also follow the same standards, some may also choose to include drug testing for sedative and anti-anxiety agents including benzodiazepines or barbiturates. Several categories of prescription medications may cause a positive urine drug screen. Proof of a legitimate prescription will usually eliminate any negative consequences from a positive drug test.

Opiate Pain Relievers

A urine drug screen for opiates is intended to test for use of the illegal drug heroin. Several prescription pain relievers are chemically related to heroin, based on the opium molecule. Drugs such as morphine, hydromorphone (Dilaudid) and oxycodone (Oxycontin) are strong pain relievers available by prescription. Other more moderate pain relievers such as codeine (Tylenol No. 3), hydrocodone (Vicodin, Norco), and propoxyphene (Darvocet) are also routinely available by prescription. Any of these medications may cause a positive result for opiates. Most of these medications will remain in the body for three to seven days with the exception of propoxyphene, which may be detectable for several weeks.

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Stimulant medications used for weight loss or the treatment of attention deficit hyperactivity disorder (ADHD) may cause a positive drug screen result for amphetamines. Adderal is one of the most commonly used agents for the treatment of ADHD. It is a mixed amphetamine salt which will remain in the urine for several days, up to one week after use. Phentermine (Fastin, Ionamin) used as an appetite suppressant may also be detected for several days. Methylphenidate (Ritalin, Concerta) will not generally cause a positive result as it is not closely related to amphetamine.


One of the most common chemicals tested for in urine drug tests is marijuana and its active component tetrahydrocannabinol (THC). A synthetic form of THC is available by prescription for the treatment of nausea and anorexia related to HIV and cancer treatment. Though its medical use is fairly rare, the controlled substance prescription product dronabinol (Marinol) may cause a positive THC urine screen for up to one month following use.

Antianxiety Agents

Antianxiety and other medications used to treat insomnia are not as commonly included on standard drug test panels, however some companies may choose to use a seven-panel drug screen which may include benzodiazepines and barbiturates. Benzodiazepines are used to treat anxiety, insomnia and some seizure disorders. Commonly used benzodiazepines such as diazepam (Valium), alprazolam (Xanax) and lorazepam (Ativan) may be detected in urine for up to one month depending upon the type. Barbiturates have been used to treat headaches, seizure disorders and insomnia but are not as commonly used as they once were. Barbiturates will often remain detectable in a specific urine drug screen for several weeks.

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Prevent Problems

If one is known to be taking a prescription medication that will cause a positive drug screen result, proof of authorization should be provided to the employer and the testing facility before testing. Bringing the prescription drug bottle, a letter from the physician who prescribed the medication or other proof of authorization will most likely eliminate any negative consequences of receiving a positive result. If one is employed in high risk occupations, medications that can alter performance may be forbidden but in most cases will be allowed if proof is provided.