Table 1: Adverse effects reported in >2% of patients taking medication for erectile dysfunction.

Table 1. Adverse Effects Reported in > 2% of patients. ^{8-10,16-18,20}
Adverse Effect by System	Sildenafil	Vardenafil	Tadalafil
Cardiovascular	Flushing	Flushing	Flushing
Central Nervous System	Headache, dizziness	Headache, dizziness	Headache
Gastrointestinal	Dyspepsia, diarrhea	Dyspepsia, nausea	Dyspepsia
Neuromuscular & Skeletal	N/A	Increased CPK	Increased CPK, back pain, myalgia
Respiratory	Nasal congestion	Rhinitis, sinusitis	Nasal congestion
Dermatologic	Rash	N/A	N/A
Ophthalmic	Abnormal vision (color changes, blurred or increased sensitivity to light)	N/A	N/A
Genitourinary	Urinary tract infection	N/A	N/A
Miscellaneous	N/A	Flu-like syndrome	Limb pain
CPK = creatine phosphokinase