Substance use disorders (SUDs) are closely linked to neurochemical imbalances in the brain. Drugs and alcohol disrupt normal neurotransmitter activity, particularly dopamine, serotonin, and glutamate systems. This dysregulation contributes to cravings, withdrawal symptoms, and compulsive substance-seeking behaviors. Chronic use alters brain reward pathways, making natural rewards less satisfying and perpetuating addiction cycles. Addressing these imbalances often requires a combination of pharmacotherapy, such as medications that stabilize neurotransmitter levels, and behavioral interventions like CBT. Understanding the neurochemical underpinnings of SUDs enables clinicians to tailor treatments, improving recovery outcomes and reducing relapse risks.