Olynth HA 1mg/ml contains Xylometazoline, which helps to narrow the blood vessels in your nose, reducing swelling of the mucous membrane (the lining in your nose), to help you breathe easier. Olynth HA 1 mg/ml also contains hyaluronic acid (in the form of sodium hyaluronate), which protects and moisturises the mucous membrane of the nose. The spray is used for short term treatment of nasal congestion with a running nose due to common cold or sinusitis.