Last updated : April 21, 2025
We can’t imagine why an employer would add caffeine to the company drug test. However, people still ask whether or not drinking coffee before a drug test is a good idea. We feel obliged to share what we know on the subject.
It may seem silly to ask if you can drink coffee before you report for a drug test. However, if you’re among those who thought so, we’ve got news for you. Coffee—or rather the caffeine found in coffee—has been linked to causing a false-positive test result for methamphetamine.
It’s true.
It didn’t happen recently though. It was back in the early days of drug testing when the tests weren’t nearly as sensitive as today.
A word to the wise
Drinking coffee before a drug test won’t cause a false positive no matter which of the three methods is used for employee drug testing.
Those tests are:
- Urine drug test
- Oral fluids, otherwise known as the mouth swab, drug test
- Hair follicle drug test
However, drinking large amounts of liquid—including water—could interfere with a urine drug test result.
Negative dilute test results
A urine drug test is deemed as a negative dilute when no drugs are detected in the specimen but the creatinine levels are out of the normal range. It’s caused by having too much liquid in the body to be processed correctly.
Employers notified that an employee received a negative dilute drug test result often allow the employee to retest. The Department of Transportation (DOT) drug testing protocol requires that the second test be observed. Some employers of the general workforce require the same. It doesn’t sound like a good time, but it could save someone their job.
Unless the employer has set up a drug-free program with a second chance provided, positive dilute drug tests result in immediate termination of employment. It’s a double whammy for an employee’s reputation though. Not only did they have drugs in their system, but diluted urine indicates to employers that the employee was trying to mask their drug use.
A few false-positive possibilities
While your morning cup of joe can’t mess up the outcome of your test, there are a few things that might.
They include:
- Antidepressants—Drugs, such as Zoloft, can be mistaken for benzodiazepines on some drug screens.
- Antibiotics—It’s a rare occurrence, but Rifampin, used to treat tuberculosis, might show up as an opiate.
- Antihistamines—The antihistamine, Diphenhydramine, might show up as PCP.
- CBD Oil—The level of THC contained in CBD products could reach traceable levels.
- 2nd hand marijuana smoke—If you’re around someone who smokes a lot your test could produce traceable levels of THC.
- Poppy Seeds—It’s “guesstimated” to take at least 3 tsps in a sitting.
- Mouthwash—The ethanol content causes the problem. It’s a form of grain alcohol.
- Weight loss pills—They curb your appetite but are similar in makeup to amphetamines.
- Coca tea—It’s made with the leaves of the same plant that produces cocaine, so…
It’s important to note that while the caffeine in your coffee doesn’t cause a false positive result perking up by slamming down an energy drink could be another story. It’s not due to the caffeine in the drinks though. It’s because some energy drinks contain ethanol. It’s a small amount, but even though you won’t catch an alcohol buzz, it might be enough to raise a red flag at the lab.
Two myths busted
If you’re an avid coffee drinker and have a drug test looming, there’s no reason to be alarmed. The false positives were rare occurrences. Not to mention that it happened back in the early days of drug testing. During the ’70s and ’80s, the tests were far less sophisticated. Back then, they say, you could achieve a negative result on the drug test by drinking massive amounts of water.
That’s not the case anymore thanks to continuing advances in drug testing technology and the ever-increasing sophistication of laboratory equipment. That’s good news for coffee drinkers and bad news for drug users. It keeps getting harder and harder to falsify a drug test.
So if you heard a rumor that drinking coffee before a drug test could cause a false positive result for amphetamines, you can put it to rest. The sophisticated laboratory equipment of today coupled with advanced technology in the creation of the tests themselves ensures there won’t be any mix-ups like there were back in the day.
You’ve also learned that drinking a lot of anything before providing a urine sample isn’t going to flush out your system. You could, however, wind up with a diluted test result which isn’t good either. Most employers require employees who receive a diluted test result to take a second drug test. And, for the record, some stipulate that it must be observed.
Too much caffeine may not result in a positive result for amphetamine these days, however, it can make you jittery or anxious and you may talk a mile a minute. These signs could raise a few red flags for the testing technician and might be misconstrued as signs of drug use.
Try getting a good night’s sleep the night before reporting for your drug test. That way you won’t be tempted to down the pot to get motivated for the day.
Just saying.
