Inhaling propane gas can be dangerous and even fatal. Propane is an odorless, colorless fuel that can cause asphyxiation when inhaled in high concentrations. Symptoms of inhaling propane gas include difficulty breathing, dizziness, nausea, headaches, and loss of consciousness. In extreme cases, it can lead to death. Inhaling propane gas should be avoided. If you suspect that you or someone else has inhaled propane gas, seek medical attention immediately.