Afrin is a popular nasal spray used to temporarily relieve nasal congestion due to colds, allergies and sinusitis. Afrin contains water and a chemical called oxymetazoline, a topical decongestant exerting vasoconstricting properties. Vasoconstricting agents cause narrowing of blood vessels and capillaries. Spraying Afrin into your nose immediately produces constriction of blood vessels in the nasal passages, which reduces swelling of nasal tissues and congestion.