What the label lists and what reports show
Sildenafil side effects
Sildenafil's FDA label: “The most common adverse reactions reported in clinical trials (≥ 2%) are headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, and rash.” FAERS holds 126,558 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is dyspnoea (13,324 reports).
- Generic listed
Check it at the source: the sildenafil FDA label on DailyMed (effective November 17, 2023, Viatris Specialty LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of VIAGRA?VIAGRA can cause serious side effects. Rarely reported side effects include: • an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis. • sudden vision loss in one or both eyes. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). It is uncertain whether PDE5 inhibitors directly cause the vision loss. Stop taking VIAGRA and call your healthcare provider right away if you have sudden vision loss in one or both eyes. • sudden hearing decrease or hearing loss. Some people may also have ringing in their ears (tinnitus) or dizziness. If you have these symptoms, stop taking VIAGRA and contact a doctor right away. […]
Source: FDA drug label, Viatris Specialty LLC, effective November 17, 2023 (SPL set d905dc8d-917f-4ea3-a4ee-a1ecf6967d4e), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions reported in clinical trials (≥ 2%) are headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, and rash.
Table 1. Most Common Adverse Reactions in Patients Treated with REVATIO 20 mg, 40 mg, 80 mg and Placebo Three Times Per Day in SUPER-1 (More Frequent in REVATIO-Treated Patients than Placebo-Treated Patients)
This table is printed in the Revatio label published by Viatris Specialty LLC of December 18, 2024; the label quoted above does not print one.
| Reaction | REVATIO 20 mg (n = 69) | REVATIO 40 mg (n = 67) | REVATIO 80 mg (n = 71) | Placebo (n = 70) |
|---|---|---|---|---|
| Headache | 46% | 42% | 49% | 39% |
| Flushing | 10% | 9% | 16% | 4% |
| Pain in Limb | 7% | 15% | 9% | 6% |
| Myalgia | 7% | 6% | 14% | 4% |
| Back Pain | 13% | 13% | 9% | 11% |
| Dyspepsia | 13% | 8% | 13% | 7% |
| Diarrhea | 9% | 12% | 10% | 6% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following are discussed in more detail in other sections of the labeling: • Cardiovascular [ see Warnings and Precautions (5.1) ] • Prolonged Erection and Priapism [ see Warnings and Precautions (5.2) ] • Effects on the Eye [ see Warnings and Precautions (5.3) ] • Hearing Loss [ see Warnings and Precautions (5.4) ] • Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives [ see Warnings and Precautions (5.5) ] • Adverse Reactions with the Concomitant Use of Ritonavir [ see Warnings and Precautions (5.6) ] • Combination with other PDE5 Inhibitors or Other Erectile Dysfunction Therapies [ see Warnings and Precautions (5.7) ] • Effects on Bleeding [ see Warnings and Precautions (5.8) ] • Counseling Patients About Sexually Transmitted Diseases [ see Warnings and Precautions (5.9) ] The most common adverse reactions reported in clinical trials (≥ 2%) are headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, and rash.
Source: FDA drug label, Viatris Specialty LLC, effective November 17, 2023 (SPL set d905dc8d-917f-4ea3-a4ee-a1ecf6967d4e), via openFDA; the full label on DailyMed
What do FAERS reports show?
126,558 reports list sildenafil among the medicines taken, each a report of something that happened, not proof the medicine caused it; 18,360 are coded as a death and 43,871 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 11 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Sildenafil: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions