This inflammation causes narrowing of the airways which allows less air to be exhaled.

Alcohol may also contribute to nocturnal hypoxaemia by causing narrowing of the upper airways.

But calcium builds up in the toilet bowl, causing narrowing of the small holes under the rim.

However in some cases, the procedure itself can cause further narrowing of the vessel, or restenosis.

Together, this causes vascular remodeling and narrowing of the pulmonary arteries.

Sometimes inflamed diverticula can cause narrowing of the bowel, leading to an obstruction.

Without appropriate treatment, the gradual increase in fluid pressure may cause increased narrowing of visual fields and eventual blindness.

Anything which causes further narrowing of this space can result in impingement syndrome.

Caffeine is a stimulant that causes narrowing of blood vessels (vasoconstriction).

It may also cause narrowing of the urethra, which makes urination difficult.