Xylometazoline
Xylometazoline is a topical decongestant applied in the nose. It narrows the blood vessels in the nasal lining, so the swollen tissue shrinks and air moves through again. It is used for short-term relief of nasal congestion during colds, sinus inflammation or allergy.
It is intended for a few days only. Beyond that the nose adapts and blocks up again as each application wears off — rebound congestion — which is the trap that turns a cold remedy into a habit that is hard to leave. Enough of the drug is absorbed through the nasal lining to affect the circulation generally, so blood pressure can shift, and it is worth mentioning to a doctor alongside heart, blood pressure or thyroid treatment. Dryness, stinging or a little bleeding from the nose are common.
Congestion that returns as soon as the effect fades, or that persists past a week, means a doctor should look at it rather than more spray being used. Palpitations, dizziness, a marked change in blood pressure, or persistent nosebleeds are also reasons to see a doctor.
Reference information, not medical advice. Discuss any change with your doctor.