Can Allergy Medication Cause A Positive Amphetamine Drug Test?

Answer

I'm so sorry to hear about the problems you've been having with the drug testing you've been undergoing. To answer your question directly, yes, several over-the-counter medications used to treat allergies and associated symptoms (e.g. nasal congestion) have been reported to cause 'false-positives' for both methamphetamine and amphetamine on urine drug screenings (i.e. assays).

Urine screenings for 'amphetamines' typically encompass all similar stimulant compounds, including:

• Dextroamphetamine
• Methamphetamine
• Methylenedioxyethylamphetamine
• Methylenedioxyamphetamine
• Methylenedioxymethylamphetamine

As far as urine drug tests go, some can distinguish between methamphetamine and other amphetamines, but the most commonly utilized ones will be fairly non-specific and detect only 'amphetamine'.

This is because most amphetamine-like compounds break down eventually in our bodies into amphetamine. Methamphetamine, for example, has at least 7 metabolites, one of which is amphetamine.

Why Do False Positives Happen?

False-positive results on urine drug screenings are relatively common, unfortunately, simply based on how these tests work.

Most urine drug screenings are 'immunoassay' based tests, which utilize antibodies to bind and react to a particular drug. False-positive results occur when an antibody binds to the wrong drug and produces a reaction.

Most often, false positives occur with drugs that have a similar molecular structure to the compound being tested for, but this isn't always the case.

The incidence rate of false positives isn't well documented, but case studies and anecdotal reports are too numerous to list. Therefore, it is important to be aware of the possibility of them occurring.

Which Drugs Can Cause False Positives For Amphetamines?

Specifically, the following over-the-counter medications have been reported to cause false-positive for methamphetamine (or amphetamine):

• Amantadine
• Brompheniramine
• Bupropion
• Chlorpromazine
• Chloroquine
• Desipramine
• Doxepin
• Labetalol
• Methylphenidate
• Phenylephrine
• Promethazine
• Pseudoephedrine
• Ranitidine
• Selegiline
• Thioridazine
• Trazodone
• Trimethobenzamide
• Venlafaxine
• Vicks inhaler (l-methamphetamine)

Some of these drugs cause false positives since they are metabolized to compounds in the body that are structurally related to amphetamine.

For example, selegiline, an antidepressant, is metabolized to l-amphetamine and l-methamphetamine.

Allergy Medications That Can Cause False Positives For Amphetamine

Of these medications listed above, the following are commonly used for allergies:

• Phenylephrine (nasal decongestant)
• Pseudoephedrine (nasal decongestant)
• Brompheniramine (antihistamine)
• Ranitidine (antihistamine H2-antagonist for stomach acid)
• Phenylpropanolamine
• Vicks Inhaler (nasal decongestant)

They have all been reported to cause false positives for amphetamines on urine drug tests. In the next sections, we'll take a look at each.

Nasal Decongestants

I want to zero in on nasal decongestants here.

The two most commonly used over-the-counter nasal decongestants are:

• Pseudoephedrine (Sudafed)
• Phenylephrine (Sudafed PE)

These nasal decongestants are well-known to cause false positives for amphetamines on urine drug tests. They are technically classified as 'stimulants' and are structurally similar to amphetamine.

In fact, most studies report that urine drug tests for amphetamine can be the most difficult to interpret due to the high risk of false positives and the sheer number of potential causative agents.

The following is from one of the most cited studies discussing urine drug screening (Urine Drug Screening: Practical Guide for Clinicians):

Unfortunately, other stimulants, anorexiants, and chemically related compounds (eg, pseudoephedrine), have been shown to produce false-positive results, making theI amphetamine assay one of the most difficult tests to interpret.

It is extremely important that you tell your doctor or testing representative all the drugs you are taking, especially if you take pseudoephedrine.

What To Do About A False-Positive Test Result

False-positive results on a urine drug screening can have very negative real-world consequences, so it is important to do what you can if you feel you got a result that was inaccurate.

First and foremost, if you are able to retake a test, see if that is a possibility. Also, be sure to disclose all of the drugs you are taking so that ones that are well-documented to cause false positives can be identified.

In more serious situations, you may want to request another testing method that is more accurate, such as gas chromatography-mass spectrometry. Drug tests using gas chromatography-mass spectrometry don't rely on antibody reactions and can accurately detect actual drug compounds in a given sample.

Final Words

Thanks for reaching out to us. I hope you found this answer helpful.