how far back can a urine test go

The length of time a urine test can detect substances varies depending on several factors, including:

1. Type of substance: Different substances have different detection windows. For example, marijuana can be detected for up to 30 days, while cocaine can be detected for up to 4 days.
2. Amount of substance used: The more of a substance used, the longer it can be detected.
3. Frequency of use: Regular use of a substance can lead to longer detection times.
4. Individual metabolism: People’s metabolisms can affect how quickly substances are broken down and excreted.
5. Type of urine test: There are different types of urine tests, including immunoassay and gas chromatography-mass spectrometry (GC-MS). GC-MS is more sensitive and can detect substances for longer periods.

Here are some general guidelines for the detection windows of common substances in urine:

• Marijuana: 1-30 days
• Cocaine: 1-4 days
• Amphetamines: 1-3 days
• Opiates: 1-3 days
• Benzodiazepines: 1-7 days
• Barbiturates: 1-7 days
• Methadone: 1-7 days
• PCP: 1-7 days
• Steroids: 1-30 days
• Alcohol: 1-5 days (using a special test called EtG)

Keep in mind that these are general estimates, and the actual detection window may vary depending on individual factors.

It’s also worth noting that some urine tests can detect substances for longer periods, such as:

• Hair tests: can detect substances for up to 90 days
• Saliva tests: can detect substances for up to 24 hours
• Blood tests: can detect substances for up to 24 hours

If you have any specific questions or concerns about urine testing, I’d be happy to help!