You can get carbon monoxide poisoning from a natural gas heater. Natural gas heaters, like all fuel-burning appliances, produce carbon monoxide as a byproduct of combustion. If a natural gas heater is not properly vented to the outside of your home, or if it is not functioning properly, carbon monoxide can build up to dangerous levels in your living space. Carbon monoxide is a colorless and odorless gas, so it is impossible to detect without a carbon monoxide detector. Symptoms of carbon monoxide poisoning can include headache, dizziness, nausea, and difficulty breathing. In severe cases, it can cause loss of consciousness and death. It is important to have your natural gas heater inspected regularly and to install a carbon monoxide detector near the heater to ensure that it is being used safely.