A suitable time interval following LEVITRA dosing for the safe administration of nitrates or nitric oxide donors has not been determined. It is crucial that you remember that you should not take more than one Levitra dose in a single hour period. Also, your doctor needs to review your medical history and make sure that you are not suffering from conditions that might be made worse by taking Levitra. Do not take vardenafil more than once a day. Physicians should inform their patients that in some patients concomitant use of PDE5 inhibitors, including LEVITRA, with alpha-blockers can lower blood pressure significantly leading to symptomatic hypotension e.Levitra is available as an oral tablet in several strengths. Your doctor will decide the best dose for you based on your needs and how you respond to the medication. Typical dose The typical. Levitra takes about 30 minutes to start working and the effects last a little longer than Viagra, about 5 hours. Staxyn dissolves in your mouth. It contains the same active ingredient as Levitra. Levitra (vardenafil hydrochloride) is an erectile dysfunction agent that works by blocking a certain enzyme (phosphodiesterase-PDE5) used to treat erectile dysfunction (impotence). What Are Side Effects of Levitra? Levitra may cause serious side effects including: hives, difficulty breathing, swelling of your face, lips, tongue, or throat.