Angel dust (PCP, or phencyclidine) is detectable in urine for 1 to 4 weeks depending on how often you’ve used it, with occasional use clearing faster and heavy use lingering much longer. The drug’s half-life ranges from 7 to 26 hours, meaning it takes that long for your body to eliminate just half the dose. But detection windows vary widely by test type, usage pattern, and individual biology.
Detection Windows by Test Type
Different drug tests look for PCP in different biological samples, and each has its own detection window.
- Urine: This is the most common test for PCP. A single use is typically detectable for about 3 to 7 days. Chronic or heavy users can test positive for up to 4 weeks, and in extreme cases even longer. Federal workplace testing uses a cutoff of 25 ng/mL for both the initial screening and the confirmatory test.
- Blood: PCP shows up in blood for roughly 24 to 48 hours after use, though this varies with dose and individual metabolism. Blood tests are less common for routine screening but may be used in emergency or forensic settings.
- Oral fluid (saliva): Saliva tests can detect PCP for 1 to 3 days. The federal cutoff for oral fluid testing is 10 ng/mL, which is lower than the urine threshold, making it slightly more sensitive at picking up recent use.
- Hair: A standard 1.5-inch hair sample covers up to 90 days of drug use history. Head hair grows about half an inch per month, so the length of the sample determines how far back the test reaches. Hair testing is the longest detection window available.
Why PCP Stays in the Body So Long
PCP is highly fat-soluble, which is a major reason it lingers. The drug crosses easily into fat tissue and brain tissue, where it essentially gets stored. Your body then releases it back into the bloodstream gradually, extending both its effects and its detectability. This is why the drug’s active effects may wear off in a few hours while traces remain in your system for days or weeks.
The half-life of PCP averages around 21 hours whether it’s smoked or injected, though the full range spans 7 to 26 hours across individuals. That wide range reflects real differences in how quickly people process the drug. After roughly five half-lives, a substance is considered essentially cleared from the blood. At the average half-life of 21 hours, that’s about 4 to 5 days for a single dose to leave the bloodstream. But because PCP accumulates in fat with repeated use, chronic users carry a much larger reservoir that takes far longer to fully release and eliminate.
How Your Body Breaks Down PCP
Your liver does the heavy lifting. A family of liver enzymes called CYP3A plays the primary role in converting PCP into metabolites your body can excrete. Several other enzyme groups also contribute, which partly explains why people with different liver function or genetics may clear the drug at different rates. The metabolites are then filtered out through the kidneys into urine.
Urine pH has a significant effect on how quickly PCP leaves your body. More acidic urine speeds up excretion, while more alkaline urine slows it down. Research published in Clinical Pharmacology & Therapeutics found that exercise decreased urine pH and increased the rate of PCP clearance through the kidneys. This is why clinical treatment for PCP intoxication has historically involved acidifying the urine and promoting fluid output, though this isn’t something to attempt on your own.
Factors That Affect Your Personal Timeline
No two people clear PCP at exactly the same rate. Several factors push your detection window shorter or longer:
- Frequency of use: This is the biggest variable. A single use clears much faster than weeks or months of regular use. Chronic use builds up PCP in fat tissue, creating a depot that slowly leaches back into circulation.
- Body composition: Because PCP is stored in fat, people with higher body fat percentages tend to retain the drug longer. PCP has a very large volume of distribution, meaning it spreads extensively throughout body tissues rather than staying concentrated in the blood.
- Metabolism and liver function: Faster overall metabolism and healthy liver function help clear the drug more efficiently. Age, genetics, and other medications that compete for the same liver enzymes can all play a role.
- Hydration and urine output: Higher urine volume has been shown to increase PCP excretion, though drinking extra water alone won’t dramatically shorten the timeline.
- Dose: Larger doses simply mean more drug to process. A higher dose extends both the duration of effects and the detection window.
What a Positive PCP Test Means
Workplace drug testing in the United States follows federal guidelines that include PCP on standard screening panels. If an initial immunoassay screen comes back positive at or above 25 ng/mL in urine (or 10 ng/mL in oral fluid), a confirmatory test using more precise technology is run at the same cutoff level. False positives for PCP are uncommon but can occasionally be triggered by certain medications, particularly some cough suppressants and antihistamines. A confirmatory test is specifically designed to rule these out.
For chronic heavy users, the combination of fat storage, a long half-life, and gradual re-release into the bloodstream means PCP can produce positive urine results for 30 days or more after the last use. If you’ve used PCP once or a handful of times, the window is much shorter, typically under a week for urine and a few days for blood or saliva. Hair remains the exception, capturing a record of use stretching back up to three months regardless of usage pattern.