Adults only (18+)

How Long Does Weed Stay in Your Bloodstream For?

Many people are surprised to learn that cannabis can remain in the bloodstream for longer than the effects last. While the high from smoking or vaping weed usually wears off within a few hours, traces of THC can be detected in the blood for a longer period. If you are preparing for a drug test or want to understand more about how your body processes cannabis, knowing how long weed stays in the bloodstream is useful. The answer depends on several factors including frequency of use, dose, and your body’s metabolism.

How THC Enters and Leaves the Blood

When cannabis is smoked or inhaled, THC enters the lungs and passes quickly into the bloodstream. It is then carried to the brain and other parts of the body, where it produces the effects most people associate with being high. Blood THC levels rise rapidly and reach their peak within minutes of inhalation. From there, the body begins to break the THC down into other compounds called metabolites. These metabolites stay in the body longer and are gradually excreted over time. Even though THC levels in the blood drop quickly, some remains detectable for a period after use.

Typical Detection Times for Blood Tests

The window for detecting THC in the blood is shorter than for other testing methods like urine or hair. In most cases, THC is only detectable in the bloodstream for up to 12 to 24 hours after a single use. However, this can vary based on the strength of the cannabis and the individual’s metabolism. For people who use cannabis frequently or in high doses, THC may be detectable for several days. In rare cases involving heavy, long-term use, blood tests have picked up THC for up to a week after the last use.

Why Blood Tests Are Used

Blood tests are typically used in situations where recent cannabis use needs to be confirmed. This includes drug-driving investigations or accidents where impairment is suspected. Unlike urine tests, which detect THC metabolites, blood tests measure the active THC circulating in the body. This makes them more accurate for determining whether someone is currently or recently under the influence. In the UK, police can request a blood sample if a roadside drug test indicates cannabis use.

Factors That Influence How Long THC Stays in Blood

The amount of time THC stays in your bloodstream depends on several personal factors. These include how much cannabis you used, how often you use it, your body fat percentage and how fast your metabolism works. THC is stored in fat cells, so people with higher body fat may retain it for longer. Hydration, diet and overall health can also influence how quickly your body clears THC from the blood. Regular users are more likely to have a slow decline in THC levels due to accumulation over time.

Does Edible Cannabis Affect the Blood Differently?

Yes, when cannabis is eaten in edible form, the THC must be digested and processed by the liver before it enters the bloodstream. This causes a slower onset of effects and can also delay the appearance and peak of THC in the blood. The high from edibles tends to last longer than smoking, and THC may be detectable in blood slightly longer because of the way it is metabolised. However, the overall detection time still usually falls within the same general range of one to three days for most users.

Conclusion

Weed can be detected in your bloodstream for a short period after use, typically between 12 hours and three days depending on how much and how often you consume it. Blood tests are designed to detect recent use and are commonly used in legal or medical settings when immediate impairment is a concern. Your metabolism, body composition and usage habits all play a part in how long THC remains in your system. If you are concerned about an upcoming test or simply want to know when your system will be clear, giving your body time to naturally eliminate THC is the most reliable option.