Before your blood test
How does alcohol affect blood test results?
Short answer
A drinking session in the 24–48 hours before a draw can raise triglycerides, liver enzymes (especially GGT and AST), uric acid and glucose, and depress blood sugar hours later. Regular heavy drinking raises GGT, MCV and triglycerides persistently. Skip alcohol for 24 hours before any lipid, liver or metabolic panel — 72 hours if you can.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
Which results does it affect?
| Marker | Direction | How long | What to do |
|---|---|---|---|
| Triglycerides | raises | 24–48 hours after drinking | No alcohol for 24–72 hours before a lipid panel [source] |
| GGT | raises | Days after heavy drinking; weeks with regular use | Abstain before the draw; tell the interpreting clinician [source] |
| AST, ALT | can raise | Days | Abstain 24–72 hours before a liver panel [source] |
| Uric acid | raises | Hours to a day | Abstain 24 hours before [source] |
| Glucose | raises or lowers | Rises while drinking, can fall hours later | Abstain the evening before a fasting glucose [source] |
| MCV (red cell size) | raises | Weeks to months of regular use | Reflects long-term intake; not a one-night effect [source] |
One night versus a pattern
A single evening of drinking mostly affects the next morning's metabolic results — triglycerides, glucose, uric acid and sometimes liver enzymes. Those settle within a day or two, which is why a 24–72 hour pause before a draw is enough for an accurate snapshot.
Regular heavy drinking leaves longer marks: GGT and MCV stay elevated for weeks after cutting back, and triglycerides and liver enzymes may remain high. Those results are accurate rather than skewed; they describe the pattern, and a clinician reads them alongside your history.
Common questions
How long should I avoid alcohol before a liver function test?
At least 24 hours; 72 hours gives a cleaner baseline for GGT and triglycerides. Regular heavy drinking will still show and that's meaningful information.
Will one glass of wine ruin my lipid panel?
A single drink the evening before has a small effect; a heavy night can raise triglycerides noticeably. When in doubt, reschedule the draw.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.