Phenylephrine and oxymetazoline can increase blood pressure and at the same time cause bradycardia.

Phenylephrine is a selective alpha-1 adrenoceptor agonist while oxymetazoline is a non-selective alpha adrenoceptor agonist. You are likely to most commonly come across phenylephrine and oxymetazoline in their us as nasal decongestants. Acting as agonists at the alpha adrenoceptors on blood vessels, they can vasoconstrict the blood vessels of the nasal mucosa. Phenylephrine can also be administered as eye drops to produce mydriasis (dilation of the pupil) without cycloplegia (paralysis of the ciliary muscle of the eye resulting in loss of accommodation and blurred near vision).  In contrast, muscarinic receptor antagonists, such as cyclopentolate, produce both mydriasis and cycloplegia.

The vasoconstriction caused by the alpha adrenoceptor agonists increases blood pressure. In fact, phenylephrine is also used as a vasopressor to treat hypotension. Our baroreceptors constantly monitor blood pressure and trigger reflex bradycardia as a compensatory measure when they detect increases in blood pressure. Thus phenylephrine and oxymetazoline are associated with increases in blood pressure and reflex bradycardia.

When treating hypotension, phenylephrine is most useful as a choice of drug for hypotensive patients who are tachycardic. Other vasopressors that increase the heart rate and force via beta-1 adrenoceptor activation, such as dopamine, adrenaline and noradrenaline, would be more likely used for hypotensive patients with normal heart rates or bradycardia.