Alcohol Detection Windows: How Long Does Alcohol Stay in Your System?

Alcohol elimination follows zero-order kinetics (constant rate, not half-life). Average rate: **0.015–0.020% BAC per hour** (≈1 standard drink/hour). Significant individual variation exists.

Detection Windows by Test

• Breath (Breathalyzer): Up to **12–24 hours** after last drink. Correlates with arterial BAC.
• Blood: Up to **12 hours** (up to 24h in some cases). Gold standard for legal/medical.
• Urine: EtG (Ethyl Glucuronide) / EtS: **12–80 hours** (up to 5 days) – detects recent exposure, not impairment. Standard urine alcohol: 12–24h.
• Saliva: 12–24 hours.
• Hair (EtG): **Up to 90 days** (1 cm ≈ 1 month); shows chronic use patterns.

Factors Affecting Elimination Rate

• Genetics: ADH/ALDH polymorphisms (e.g., ALDH2*2 in East Asians → flushing, slower clearance).
• Sex: Women have lower gastric ADH, higher body fat % → higher BAC per drink.
• Body Weight/Composition: Higher weight → larger volume of distribution → lower BAC.
• Age: Slower metabolism, less body water → higher BAC.
• Food: Delays gastric emptying → slower absorption, lower peak BAC.
• Liver Health: Cirrhosis reduces metabolic capacity.
• Medications: Some inhibit/induce CYP2E1 (minor pathway at high BAC).

Common Myths

• Coffee, cold showers, exercise, "sweating it out" **do not accelerate elimination**.
• Only time reduces BAC.

Practical Estimation

• Widmark Formula: BAC = (Grams ethanol × 100) / (Body weight in g × r) – (β × t).
• r = 0.68 (men), 0.55 (women). β = 0.015–0.020 %/hr.
• Online calculators provide rough estimates only; **not for legal reliance**.