Does Doxepin show up on a drug test? 

Does Doxepin show up on a drug test? 

Yes, Doxepin can show up on a drug test as this antidepressant can cause false positives for Amphetamines. Doxepin is a tricyclic antidepressant (TCA) and the entire class of these antidepressants is known for causing a false positive for Amphetamines (1,2). 

These medications are not structurally similar to Amphetamines and they are not generally considered drugs of abuse – including Doxepin – but they can make a drug test positive. 

This is probably because of the cross-reactivity of antibodies that are used in preliminary drug urine immunoassays. 

This drug testing procedure can lead to false positives because of its inaccuracy and this is usually why confirmatory tests are preferred to confirm the findings of urine drug Immunoassays. 

How long does Doxepin stay in your system? 

Doxepin has a half-life of about 20-50 hours, depending on different factors like your age, weight, dosage strength, frequency, duration of treatment, any underlying health condition, and overall physiological well-being. 

It usually takes 5 half-lives by Doxepin to get completely washed out from your system. This indicates that it could take up to 5-6 days for your body to completely get rid of this antidepressant. 

How to avoid Doxepin showing up on a drug test? 

Doxepin is well known to show a false positive and the only way to avoid it is to opt for an accurate drug testing procedure. 

You can’t simply skip taking Doxepin before your test as it’s an antidepressant and it should never be stopped abruptly, especially if you have been taking the medication for a long time. 

You can simply talk to your healthcare provider and inform the drug testing authority about your prescription Doxepin – a medication that is capable of causing a false positive. 

Again, don’t ever stop taking your Doxepin abruptly. Antidepressants are supposed to be tapered off before stopping them, and skipping them for your test can cause some disturbing withdrawal-like symptoms. 

It’s best to continue taking your antidepressant the way your doctor has directed and inform the drug testing authority prior to the test.

Doxepin may cause some side effects as well, like nausea, diarrhoea, weight gain, etc. However, such medications should never be stopped cold turkey because of the potential withdrawal symptoms.

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Alyson Schwebach, Jennifer Ball. Urine Drug Screening: Minimizing False Positives and False Negatives to Optimize Patient Care. US Pharm. 2013;38(12):1-6. Available at:


Merigian KS, Browning R, Kellerman A. Doxepin causing false-positive urine test for amphetamine. Ann Emerg Med. 1993 Aug;22(8):1370. doi: 10.1016/s0196-0644(05)80129-5. PMID: 8333649. Available from:

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