Some signs of antifreeze poisoning include rapid breathing, no breathing, decreased urine output or blood in the urine, blindness or blurred vision and low blood pressure, notes the United States National Institutes of Health's MedlinePlus. Other symptoms include a change in the body's acidic/base balance, organ failure, rapid heartbeat and leg cramps. Additional symptoms are convulsions, slurred speech, fatigue, dizziness and weakness.
In addition to these symptoms, the person may experience stupor or lack of alertness and have an unsteady walk, notes Mayo Clinic. The person's fingernails and lips may turn blue, and there may be gastrointestinal symptoms present, including vomiting and nausea. Immediate emergency medical care is required for antifreeze poisoning.