Challenges with Oral Fluid Testing: Dry Mouth and Split Samples

As oral fluid testing becomes more common in DOT drug testing, it’s important to address practical challenges like dry mouth and the role of split samples. This article provides a simple overview to help safety-sensitive employees and employers better understand the process.

What Happens When There’s Not Enough Saliva?

Dry mouth is often caused by nervousness, dehydration, or substances like amphetamines. It can interfere with the ability to produce a valid oral fluid sample.

If an employee can’t produce enough saliva, they may rinse with up to 8 ounces of water. After rinsing, a 10-minute waiting period is required before the collection attempt can be made again. Drinking the water isn’t mandatory, and refusal to do so does not count as a refusal to test.

If the employee still can’t provide a sufficient sample, the employer must switch to a urine test. This isn’t optional—it should be outlined clearly in the company’s drug testing policy.

Split Samples: Protecting Test Accuracy

To ensure fairness, DOT oral fluid testing uses a split sample process. The collector uses one swab, which is broken in half and placed into two separate containers—one for initial testing and the other reserved for confirmation testing if needed. Both samples are sent to the lab, maintaining a high standard of reliability and transparency.

How Long Does Testing Take?

While oral fluid testing is often conducted on-site, the results aren’t instant. Laboratory processing typically takes anywhere from 30 minutes to a few days, depending on the testing lab’s schedule.

In cases like random or follow-up testing, employers may still prefer urine tests because they offer a longer detection window for identifying patterns of use.

What Employers and Employees Should Know

For Employers:
Update your testing policies to include clear procedures for handling insufficient saliva collections and when urine testing must be used instead. Consider training DOT-regulated staff to collect oral fluid samples on-site for added convenience.

For Employees:
If you experience dry mouth, rinsing with water and waiting the designated time can help. And remember, oral fluid testing isn’t a roadside swab. It follows the same rigorous, lab-based process as urine testing.

Final Thoughts: Handling Oral Fluid Testing Challenges

Understanding how to address dry mouth and the importance of split samples helps ensure a smooth, compliant testing experience. With clear policies, proper training, and DOT safeguards in place, employers and employees can navigate oral fluid testing confidently and fairly.

Need help reviewing your company policy or preparing for oral fluid collection? I’m here to help.