This is due to the alpha-mimetic activity of pseudoephedrine in combination with other vasoconstrictors such as bromocripitine, pergolide, lisuride, cabergoline, ergotamine, dihydroergotamine or any other decongestant medicinal product used as a nasal decongestant, either by oral route or by nasal route (phenylpropanolamine, phenylephrine, ephedrine, oxymetazoline, naphazoline…).