You must refer to the pharmacist, if in your conversation you discover that your patient:

takes other medication (especially for blood pressure or mental health conditions).
has other health conditions, or is pregnant, or breastfeeding.
has mucous that is thick and coloured, as there may be a secondary bacterial infection.
has been using a decongestant nasal spray for longer than 3 days.

And refer if you are unsure whether it is an allergic reaction, like hay fever, or a viral infection, such as a cold.

Part 4: When to refer