Can marijuana cause an increase in heart rate?

No. Smoking marijuana increases your heart rate, cigarettes slow it down.

^This person is extremely mis informed.

Smoking marijuana does increase your heart rate slightly, however it is hardly noticed.

Cigarettes though, increase your heart rate also. Nicotene, which is the active ingredient in cigarettes which you are obviously unaware of, is a stimulant.

Therefore, increasing the ammount of blood pumped along with the pulse rait, together increasing cardiac output.

gtfo.