Antidepressant medications can be highly effective for many people with depression, particularly for moderate to severe cases. These medications work by altering the levels of neurotransmitters in the brain, such as serotonin and norepinephrine, which are linked to mood regulation. However, effectiveness can vary from person to person, and it may take several weeks to notice improvements. Sometimes, finding the right medication and dosage requires a trial-and-error approach under a doctor’s supervision.