Shipping: Discreet, fast shipping is a must. Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily. ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed. Some medications should not be taken with sildenafil. If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. · Cost. To learn about the cost of Viagra, refer to this article. Details on your condition. For details about ED, see this list of related articles, as well as ourmen’s health hub. Cialis lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung .