Knowing the signs and symptoms of abuse can help you get your loved one quality detox and treatment. Observable signs of substance abuse can include anxiety, depression, irritability, and even suicidal thoughts or behavior. It also includes Euphoria, Irritability, Inappropriate anger, Paranoia, Impaired judgment, Restlessness, Inability to sleep, Hypersensitivity to sight, sound, touch, Dilated pupils, Gastrointestinal complications, including abdominal pain and nausea, Poor appetite and weight loss, Muscular weakness, Increased body temperature, heart rate, and blood pressure.