Afrin 0.05% is a medicine used to treat nasal congestion (blocked nose) caused by the common cold or flu, hay fever and other allergies. It shrinks blood vessels in your nose to relieve nasal congestion and blockage. Afrin 0.05% should be used as you have been advised by your doctor. Normally you should blow your nose gently before using it, keep one nostril closed while applying the medicine into the other and then sniff hard to make sure it reaches deep into the nose. Then repeat the same for the other nostril. It provides relief very quickly and can last for several hours. It provides only temporary relief but do not use it more often or for longer than recommended. If you use this medicine too often or for too long, it may worsen your symptoms rather than improve them. The most common side effects are irritation or discomfort to the nose and sneezing. These are usually mild but if they bother you or do not go away, your doctor may be able to suggest ways of preventing or reducing them. It is generally a safe medicine but, before taking it, talk to your doctor about any health problems you have such as heart problems or high blood pressure (hypertension) or overactive thyroid gland or glaucoma (increased pressure in the eye) or prostate enlargement. Let your doctor know about any other medicines you are taking to make sure you are safe. Ask your doctor for advice before using this medicine if you are pregnant or breastfeeding.