The medicated Sinex nasal decongestant sprays use oxymetazoline, listed on labels as Oxymetazoline Hydrochloride (Oxymetazoline HCl).
For the medicated oxymetazoline formulations, relief is commonly reported to last up to about 12 hours, with many users noting hours-long benefit around that timeframe.
Labels commonly advise consulting a doctor if you have conditions such as diabetes, thyroid disease, high blood pressure, heart disease, difficulty urinating, or if you are pregnant or nursing. They also recommend medical advice for other significant health issues—check the product label for the full list.
Product descriptions and customer feedback describe very fast onset—labels and reviewers commonly report near-immediate clearing, with relief occurring in seconds to minutes.
Review summaries highlight fast, reliable relief—many users report immediate or near-immediate clearing and hours-long benefit. Some reviewers report sensory effects such as a menthol burn or brief headache, while others report no burning or irritation.