Test Kit Research & Comparison Center
Home screens and laboratory confirmation
A home test is the first step, not the last word. Here is what each step can tell you.
Confirmation costs extra
The random scheduling and accountability service is free. Test kits and any laboratory testing are purchased separately. P in the Cup does not perform the testing or certify these products, and does not arrange laboratory testing.
A two-step process
Home tests are qualitative: they show whether a particular drug may be present, not how much. FDA's advice after a positive home result is to send the sample to a laboratory for a second test and to take no serious actions until you have the laboratory's result.
FDA-cleared labelling says the same. The over-the-counter test in K091588 is described as "the first step in a two step process", with materials for shipping the urine specimen to a laboratory, and its results as "only preliminary data, which should be confirmed by other methods such as gas chromatography/mass spectrometry (GC/MS)". The prescription point-of-care test in K091612 names GC/MS or LC/MS as the preferred confirmatory method.
Home screen and laboratory test compared
| Question | Home screen | Laboratory confirmation |
|---|---|---|
| What it reports | Whether a drug may be present above the cutoff (qualitative) | A preliminary analysis and, if positive, a more complete analysis of the sample |
| How fast | Minutes, read by eye within the window in the instructions | Not immediate; the sample goes to a laboratory |
| Status of a positive | Preliminary | Confirmed analytical result (interpretation still needs care; see below) |
| Cost | The kit price | Extra, unless the kit's price includes laboratory analysis; check before buying |
What a preliminary positive means
A positive home result is preliminary, not proof. FDA says foods, supplements, beverages and medicines can affect results, and that some over-the-counter medicines can give the same result as amphetamines. A positive for a prescribed medicine does not on its own mean the medicine is being misused. Near the cutoff, screens also disagree with the expected result more often (see near-cutoff behaviour).
What a negative means
A negative applies only to the substances tested, at the kit's cutoffs, within its detection windows. FDA says no drug test of this type is 100% accurate, and a negative can happen if the test looked for the wrong drug, the sample was collected too early or too late, or the test was stored incorrectly or out of date. FDA notes that you can test again later. A negative does not establish that no drug was used.
Why laboratory confirmation matters
FDA calls laboratory tests the most reliable way to confirm drugs of abuse. Laboratories do a preliminary analysis and, if it is positive, a more complete analysis of the sample. FDA notes that for home collection kits, which send the sample to a laboratory rather than reading it at home, the purchase price usually covers the laboratory analysis.
Federal workplace testing, which SAMHSA oversees, also has results reviewed by a Medical Review Officer, a licensed physician, and SAMHSA notes that even a laboratory-confirmed positive does not automatically mean someone misused drugs. In a personal agreement, that is a good reason to treat any result calmly and to agree in advance what happens after a preliminary positive.
Agree on these before anyone tests
- Which laboratory, or which mail-in option, will be used after a preliminary positive, and who pays.
- What happens while waiting for the laboratory result.
- Which prescribed medicines each person takes that could affect a screen.
- That a negative is not proof of anything beyond the substances and cutoffs tested.
Sources
- U.S. Food and Drug Administration, "Drugs of Abuse Home Use Test" (content current as of 27 September 2018; read 21 October 2026). Supports: qualitative results; laboratory second test and no serious action until the result; interference from foods, supplements, beverages and medicines; over-the-counter medicines and amphetamine results; prescribed medicines; reasons for a wrong negative; no test of this type is 100% accurate; read window.
- U.S. Food and Drug Administration, "Drugs of Abuse (Collection Kit)" (content current as of 27 September 2018; read 21 October 2026). Supports: laboratory tests are the most reliable way to confirm; preliminary and more complete analysis; price usually covers the analysis.
- FDA 510(k) decision summary K091588, PDF page 3 (read 21 October 2026). Supports: two-step process and GC/MS confirmation wording.
- FDA 510(k) decision summary K091612, PDF page 2 (read 21 October 2026). Supports: GC/MS or LC/MS as the preferred confirmatory method.
- SAMHSA, "Workplace Drug Testing Resources" (read 21 October 2026). Supports: Medical Review Officers are licensed physicians who review laboratory results; a laboratory-confirmed positive does not automatically mean misuse.
General education only, not medical or legal advice. For questions about a particular result, speak to a healthcare professional.
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