The most common side effects of Levitra include headaches, flushed skin, and a stuffy or runny nose, but please ask your doctor for a complete list. Also, be sure to tell your physician IMMEDIATELY if you experience an erection that lasts longer than four hours, alterations in your vision, or any other significant changes. Levitra should not be taken in conjunction with medications that contain nitrates and should be avoided by men whose doctors have asked them not to engage in sex. Ask your doctor for a full list of medications and conditions that should not be combined with Levitra. Many men suffer from some sort of erectile dysfunction, and Levitra can be effective at easing symptoms. However, this drug should always be used under the direct care of a physician.