Does fish oil show up on a drug test? 

Does fish oil show up on a drug test? 

No, fish oil does not show up on a drug test. Fish oil is used as a source of Omega-3 fatty acids which are known as ‘Good fats’ and they are associated with a whole lot of health benefits (1). 

Fish oil does not contain any ingredient which makes it a controlled substance or a drug of abuse. It is also not known for causing a false negative for any of the scheduled drugs. 

So if you’re taking fish oil capsules for their medical benefits, it will definitely not show up or make you fail the drug test. False positives are common, indeed, but with preliminary testing procedures like urine drug immunoassays (2). 

Modern drug testing procedures like Gas Chromatography – Mass spectroscopy (GC-MS) deliver accurate results (3). If that’s what your testing procedure is based on, you don’t have to worry about false positives. 

What medications show up on a drug test?

Most medications that show up on a drug test are controlled substances or drugs of abuse. These drugs are associated with several psychological side effects and are illegal to use without a prescription because of their habit-forming or addictive nature. 

Supplements like fish oil capsules or mineral, vitamin, or amino acid supplements like L-tyrosine supplements don’t show up in a drug test, as they are not drugs and these nutrients are generally a part of our body. 

Some common examples of drugs that are detected in drug tests include: (4,5)

  • Opioids – Heroin, Morphine, Codeine, Oxycodone, Hydrocodone.
  • Cannabinoids – THC (Tetrahydrocannabinol) is found in marijuana.
  • Amphetamines – Amphetamine, Methamphetamine (Meth), MDMA (Ecstasy).
  • Benzodiazepines – Diazepam (Valium), Alprazolam (Xanax), Lorazepam (Ativan).
  • Cocaine – Cocaine, Crack Cocaine.
  • Barbiturates – Phenobarbital, Secobarbital.
  • Phencyclidine (PCP) 
  • Methadone
  • Synthetic cannabinoids – Synthetic Marijuana (Spice).

Final words

To sum up, fish oil is not detected in drug tests. It is not linked to any of the controlled drugs and is not something a standard drug test looks for. 

If you are taking any medication that is known for causing a false positive, please reach out to your healthcare provider to discuss ways to prevent failing a drug test. 

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Harris WS. Fish oil supplementation: evidence for health benefits. Cleve Clin J Med. 2004 Mar;71(3):208-10, 212, 215-8 passim. doi: 10.3949/ccjm.71.3.208. PMID: 15055244.


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:


Ramoo B, Funke M, Frazee C, Garg U. Comprehensive Urine Drug Screen by Gas Chromatography/Mass Spectrometry (GC/MS). Methods Mol Biol. 2016;1383:125-31. doi: 10.1007/978-1-4939-3252-8_15. PMID: 26660182. Available from:


McNeil SE, Chen RJ, Cogburn M. Drug Testing. 2023 Jan 16. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 29083751.


Moeller KE, Lee KC, Kissack JC. Urine drug screening: practical guide for clinicians. Mayo Clin Proc. 2008 Jan;83(1):66-76. doi: 10.4065/83.1.66. Erratum in: Mayo Clin Proc. 2008 Jul;83(7):851. PMID: 18174009.