Why can nicotine withdrawal cause irritability and difficulty concentrating?

Nicotine withdrawal causes irritability and difficulty concentrating because the brain has physically adapted to the regular presence of the substance.

Nicotine functions as a stimulant that binds to acetylcholine receptors in the brain, triggering the release of neurotransmitters such as dopamine, norepinephrine, and serotonin. These chemicals play essential roles in regulating attention, mood, and reward pathways.12

With continued use, the brain alters the number and sensitivity of these receptors, creating a state of physical dependence. When nicotine intake is stopped or reduced, the brain’s signaling is disrupted, leading to withdrawal symptoms as the body struggles to function without the external stimulation it has come to rely on. This chemical imbalance manifests as irritability, anxiety, and cognitive difficulties, which are hallmark signs of nicotine use disorder.2