Marijuana (THC) typically stays detectable in the blood for a relatively short period compared to other testing methods. For occasional users, THC can be detected in blood for about 1 to 2 days (24 to 48 hours) after use. In chronic or heavy users, detection in blood may extend up to 7 days or even longer, with some studies showing detection up to 25 days in heavy users

. More specifically:

• Occasional use: THC detectable in blood for 3 to 4 hours, with metabolites (like 9-carboxy-THC) detectable for 2 to 3 days

• Frequent/heavy use: THC detectable for 4 to 8 hours, metabolites up to two weeks or more

• General range: Blood tests detect THC from a few hours up to 1-2 days for most users, but chronic heavy use can extend this window to about a week or longer

This is shorter than detection windows for urine (3 days to over 30 days depending on use), saliva (up to 72 hours), or hair (up to 90 days)

. Factors affecting detection time include frequency of use, body fat percentage (THC is stored in fat cells), metabolism, potency, and method of consumption

. In summary, marijuana stays in the blood typically for 1-2 days in occasional users, but can be detected for up to a week or more in chronic heavy users, with metabolites lingering longer depending on usage patterns