Smelling irritating gas will cause sneezing when you have nasal congestion, which will discharge the secretions from the nasal cavity and can temporarily relieve the symptoms of nasal congestion. The irritating smell of onion is relatively strong and will stimulate the nasal mucosa causing sneezing, which can provide relief to nasal congestion, but only temporary relief. If there is still inflammation in the nasal cavity, there will continue to be inflammatory secretions exuding when there is congestion and edema, which will cause the symptoms of nasal congestion. It needs to be actively treated with anti-inflammatory and anti-viral drugs, and also needs to be treated with a combination of nasal ventilating drugs. At this time, it also needs to drink more water, pay attention to keep warm, and also needs to pay attention to rest to facilitate the recovery of the disease.