Contrary to vasodilators, vasoconstrictors are substances that act to shrink the blood vessels, that is to say, their narrow lumen. Vasoconstrictors are used clinically to increase blood pressure, or more often to reduce local blood flow.
Decongestants containing a vasoconstrictor drugs are used to treat certain types of rhinitis, but cannot be given more than a few days because paradoxically it may lead to worsening nasal congestion. The vasoconstrictor effect can indeed spread to other vessels and cause cardiovascular risk. Locally, the risk is atrophy of the nasal mucosa and therefore, atrophic rhinitis (with constantly runny nose). It is, therefore, important to use these products with vigilance and during a short period of time.
For our part, we discourage all except extreme emergency use of nasal vasoconstrictor in local use because of the attack of the nasal mucosa.