Common (4–10% frequency) side effects of<unk>  include dizziness, headache, drowsiness, lack of energy, weakness, palpitations, and nausea. Less frequent (1–4%) side effects include vomiting, diarrhea, constipation, edema, orthostatic hypotension, dyspnea, syncope, vertigo, depression, nervousness, and rash. A very rare side effect of<unk>  is priapism. One phenomenon associated with<unk>  is known as the "first dose response", in which the side effects of the drug specifically orthostatic hypotension, dizziness, and drowsiness are especially pronounced in the first dose. Orthostatic hypotension and syncope are associated with the body's poor ability to control blood pressure without active α-adrenergic receptors. People on<unk>  should be told to rise to stand up slowly, since their poor baroreflex may cause them to faint if their blood pressure is not adequately maintained during standing. The nasal congestion is due to dilation of vessels in the nasal mucosa.
Prazosin
Phenylephrine
Acebutolol
Terazosin
Doxazosin
Tamsulosin
Silodosin
Hydrastine