The new research, presented at the British Thoracic Society Winter Meeting, found that so-called "nasal douching" led to improvements in chest and nasal symptoms among people with severe asthma and rhinosinusitis - an inflammatory condition of the nasal passages and paranasal sinuses.
Experts taught 30 patients how to rinse their nasal passages with a simple saline rinse kit, initially one or two times a day.
Their symptoms were assessed before starting treatment and again three months later.
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After three months, 88 per cent of patients reported improved nasal symptoms and 62 per cent reported improved chest symptoms.
Meanwhile, 83 per cent showed clinically significant improved "asthma control" scores, the authors said.
Lead researcher Anita Clarke, senior physiotherapist from Birmingham Regional Severe Asthma Services and member of the British Thoracic Society, said the study showed that nasal irrigation can help reduce nasal symptoms and also reduce asthma symptoms.
"Two thirds of patients with severe asthma also suffer with rhinitis - this can lead to nasal congestion, forcing patients to adopt abnormal breathing patterns such as mouth-breathing, which exposes the airways to cold dehumidified air," she said.
"This, along with the abnormal breathing pattern itself, can make asthma symptoms worse."
Sonia Munde, head of Asthma UK's Helpline, said some people with asthma also have seasonal or year-round rhinitis, which causes inflammation of the lining of the nose.
"We suggest nasal douching - a simple procedure where you sniff saline solution into your nostrils to remove any debris, clear away any allergens, prevent infection, and keep your nose clean and healthy," she said.
