Revatio is a prescription medication used to treat pulmonary arterial hypertension (PAH), a condition where blood pressure in the arteries connecting the heart to the lungs is dangerously high. It contains the same active ingredient as Viagra (sildenafil) but is prescribed at a lower dose, taken multiple times daily, and approved for a completely different condition. The goal of treatment is to improve your ability to exercise and slow the progression of the disease.
How Pulmonary Arterial Hypertension Affects the Body
In PAH, the small arteries in your lungs become narrowed and stiff. This forces the right side of your heart to work much harder to push blood through, and over time the heart can weaken. Symptoms include shortness of breath during routine activities, fatigue, chest pressure, and swelling in the ankles or legs. Revatio is specifically approved for WHO Group I PAH, which includes cases caused by genetic factors, connective tissue diseases, congenital heart defects, and idiopathic (unknown) causes.
How Revatio Works
The smooth muscle lining your pulmonary arteries relies on a signaling molecule called cGMP to relax. An enzyme in those cells constantly breaks cGMP down. Revatio blocks that enzyme, allowing cGMP to accumulate. The result is that the pulmonary arteries relax and widen, reducing the pressure your heart has to pump against. This effect is concentrated in the lungs, though a milder drop in blood pressure can occur throughout the body as well.
How Revatio Differs From Viagra
Both products contain sildenafil, but they are prescribed very differently. Viagra comes in 25 mg, 50 mg, and 100 mg tablets taken once before sexual activity. Revatio comes as a 20 mg tablet (or a liquid suspension) taken three times a day, spaced four to six hours apart. An intravenous form also exists for patients who temporarily cannot take the oral version. Generic 20 mg sildenafil tablets approved for PAH are now widely available, which has significantly lowered the cost of treatment.
Because the two products serve different purposes and follow different dosing schedules, they should not be used interchangeably. You would not substitute a single Viagra tablet for three daily Revatio doses, and vice versa.
Common Side Effects
In the main 12-week clinical trial of 277 adults with PAH, headache was the most frequently reported side effect, occurring in roughly 46% of patients on the standard 20 mg dose compared with 39% on placebo. Other common reactions at the 20 mg dose included:
- Flushing: 10% (vs. 4% on placebo)
- Indigestion: 13% (vs. 7%)
- Diarrhea: 9% (vs. 6%)
- Back pain: 13% (vs. 11%)
- Muscle pain: 7% (vs. 4%)
- Limb pain: 7% (vs. 6%)
Nosebleeds were notably more common in patients whose PAH was related to connective tissue disease, affecting about 13% of that subgroup. Patients taking blood thinners that work through vitamin K also had a higher nosebleed rate (9% vs. 2%).
Serious Risks to Be Aware Of
Because Revatio relaxes blood vessels, it can cause a mild, transient drop in blood pressure. This effect becomes dangerous when combined with certain other medications. Revatio is strictly contraindicated with any form of nitrate, including nitroglycerin tablets, patches, sprays, and ointments, as well as isosorbide (used for chest pain) and recreational “poppers” (amyl nitrate or butyl nitrate). Taking them together can cause blood pressure to plummet to life-threatening levels. The same applies to riociguat, another medication used for pulmonary hypertension.
Rare but serious events reported with sildenafil-based medications include sudden vision loss from reduced blood flow to the optic nerve, and sudden hearing loss sometimes accompanied by ringing in the ears or dizziness. Prolonged erections lasting more than four hours have also been reported and require emergency treatment to prevent permanent damage.
Patients with a rare subtype called pulmonary veno-occlusive disease (PVOD) may actually worsen on any pulmonary vasodilator, including Revatio, because the blockage in their lungs is in the veins rather than the arteries.
Use in Children
Revatio is approved for adults. The FDA has issued safety communications recommending against its use in children with pulmonary hypertension, after post-marketing data raised concerns about increased mortality at higher doses in pediatric patients. A follow-up clarification noted that low doses might still be considered on a case-by-case basis, but this remains an area of caution rather than routine practice.
Off-Label Uses
Because sildenafil improves blood flow by relaxing small arteries, doctors sometimes prescribe it off-label for conditions involving poor circulation to the extremities. The most established off-label use is for Raynaud’s phenomenon, particularly in patients with systemic sclerosis (scleroderma) whose fingers develop painful ulcers from restricted blood flow. Expert consensus guidelines from rheumatology groups list sildenafil as a treatment option when first-line therapies for Raynaud’s are not enough, or when digital ulcers are not healing. No sildenafil product carries an official approval for these uses, so the decision is made on an individual basis between patient and physician.