How Long After Smoking Marijuana Can I Drive?

The effects of smoking marijuana are usually reduced after three to four hours, but can last for anything up to a whole day.

If you are pulled over in your vehicle, then a police officer can carry out a mouth swab test which can detect THC (the active component of marijuana) in your saliva for several hours. However, this test - as well as how long the effects last - depends almost entirely on how much marijuana you have inhaled.

The effects of using marijuana

• Rapidly increases heart rate.
• Increases blood pressure.
• Increases breathing rate.
• Reddening of the eyes.
• Drying of the mouth.
• Increases appetite, which is known as the 'munchies'.
• Slows down reaction times.
• Inaccurate sense of time.
• May lead to paranoia.
• Random and deep thoughts.
• Can lead to short-term memory loss.
• May cause or aggravate feelings of depression.
• Heightens anxiety.

These effects could be significantly reduced after four hours but would still affect your ability to drive for several hours after this, even if you do not realise it. It's better to be safe and not risk driving within 24 hours of inhaling marijuana!