Major side effects associated with Ativan use and/or abuse include: Confusion. Lack of muscle control. Blood in urine or stool. Stomach pain. Weight loss. Tremors. Overdose. Addiction.Effects on the Mind · Signs of an Ativan Overdose. Mar 10, - Learn about Ativan (Lorazepam) may treat, uses, dosage, side effects, drug interactions, warnings, patient labeling, reviews, and related. Mar 16, - Lorazepam – Weight Gain & Other Side Effects. Dizziness. Sedation. Motor function impairment. Loss of concentration. Loss of appetite. Weight loss. Muscle soreness or tension. Headache.