Can an overdose of sertraline cause a false‑positive urine drug screen?

Can Sertraline Overdose Cause a False-Positive Urine Drug Screen?

Yes, sertraline can cause false-positive urine drug screens, specifically for benzodiazepines, and this occurs at therapeutic doses—not just in overdose situations. The FDA drug label explicitly states that "false-positive urine immunoassay screening tests for benzodiazepines have been reported in patients taking sertraline" 1.

The Mechanism and Clinical Context

The false-positive results occur due to lack of specificity in immunoassay screening tests, not because of the dose or overdose amount 1. This is a fundamental limitation of the immunoassay methodology used in most rapid urine drug screens:

• Immunoassays are susceptible to cross-reactions with structurally similar compounds, leading to false-positive results 2
• The cross-reactivity happens at the screening level, regardless of whether the patient took a therapeutic dose or overdosed
• Sertraline specifically cross-reacts with benzodiazepine immunoassays 1, 3

Evidence Strength

A retrospective two-year chart analysis found that 26 out of 98 false-positive benzodiazepine screens (27%) were associated with concomitant sertraline prescriptions when confirmatory testing ruled out actual benzodiazepine use 3. Multiple literature reviews consistently identify sertraline as causing false-positive results for benzodiazepines 4, 5, 6, 7.

Critical Clinical Action Required

The FDA label explicitly states that confirmatory tests such as gas chromatography/mass spectrometry will distinguish sertraline from benzodiazepines 1. This is your definitive next step:

• Always order confirmatory GC/MS testing when a positive benzodiazepine screen occurs in a patient taking sertraline
• False-positive results "may be expected for several days following discontinuation of sertraline therapy" 1
• Do not make clinical decisions based solely on immunoassay results in patients on sertraline

Important Caveats

The dose or overdose status does not determine whether a false-positive occurs—it's the presence of sertraline itself that causes the cross-reactivity 1. In overdose situations specifically:

• The FDA reports that overdoses up to 13.5 grams have been survived 1
• Common overdose symptoms include somnolence, vomiting, tachycardia, nausea, dizziness, agitation, and tremor 1
• Emergency management should be based on clinical presentation, not drug screen results 2

Practical Algorithm

When encountering a positive benzodiazepine screen in a patient taking sertraline:

1. Assume it is false-positive until proven otherwise with confirmatory testing
2. Order GC/MS confirmation immediately—do not delay treatment decisions waiting for this
3. Review the complete medication list for other potential cross-reactants 2
4. In overdose scenarios, manage clinically based on vital signs and symptoms, not the drug screen 2, 1

The guideline literature emphasizes that drug test results must always be interpreted within the context of complete medical history, including all prescribed medications 2. The presence of sertraline on a medication list should immediately raise suspicion for a false-positive benzodiazepine result.