Which ED Medication Has the Fewest Side Effects?
The label rates differ by drug and dose, but no head-to-head trial crowns one pill. Here is what the numbers actually allow you to say.
The short version
- All four approved ED tablets share the same common side effects: headache, flushing, indigestion and nasal congestion.1234
- In a 2015 analysis of 72 trials, tadalafil 10 mg had the lowest overall adverse event rate at starting doses and sildenafil 50 mg the highest.5
- A 2013 analysis of 118 trials found no major difference in safety among the agents at recommended doses.6
- Dose matters: in sildenafil's fixed-dose trials, abnormal vision was reported by 1% on 25 mg and 11% on 100 mg.1
- Sudden vision or hearing loss, or an erection over four hours, needs urgent medical care on every one of these drugs.13
No ED tablet has been shown to be gentler than the rest in head-to-head trials. The FDA labels for sildenafil, tadalafil, vardenafil and avanafil list the same short set of common side effects: headache, flushing, indigestion and nasal congestion.1234 What differs is how often each one shows up and which extra side effect each drug is known for. A 2015 analysis of 72 trials found tadalafil 10 mg had the lowest overall rate of adverse events at starting doses, and sildenafil 50 mg the highest.5 Dose matters as much as drug, and so does your own health history.
This guide lays the label numbers side by side, explains why they cannot be compared like a scoreboard, and covers the rare side effects that mean stopping the medicine.
What side effects do all ED pills share?
The four approved tablets belong to one class, so their common side effects overlap. In the pivotal trials each label reports headache, flushing, nasal congestion or rhinitis, and dyspepsia (indigestion) more often than placebo.1234 Back pain and muscle aches show up on several labels too. These reactions are usually described as mild, and the Viagra label notes that the visual changes it reports were mild and transient.1
How do the label side effect rates compare?
These figures come straight from each drug's FDA label. They are the percentage of men reporting each reaction in the company's placebo-controlled trials at the doses shown.
| Reaction | Sildenafil (flexible dose) | Tadalafil 10 or 20 mg, as needed | Vardenafil (5 to 20 mg) | Avanafil 100 or 200 mg |
|---|---|---|---|---|
| Headache | 16% (placebo 4%)1 | 11% to 15% (placebo 5%)2 | 15% (placebo 4%)3 | 6.9% to 10.5% (placebo 1.7%)4 |
| Flushing | 10% (placebo 1%)1 | 3% (placebo 1%)2 | 11% (placebo 1%)3 | 4.3% to 4.0% (placebo 0%)4 |
| Indigestion | 7% (placebo 2%)1 | 8% to 10% (placebo 1%)2 | 4% (placebo 1%)3 | Under 2%4 |
| Nasal congestion or rhinitis | 4% (placebo 2%)1 | 3% (placebo 1%)2 | 9% rhinitis (placebo 3%)3 | 2.9% to 2.0% (placebo 1.1%)4 |
| Back pain | 2%, same as placebo1 | 5% to 6% (placebo 3%)2 | 2.0% (placebo 1.7%)3 | 2.0% to 1.1% (placebo 1.1%)4 |
| Abnormal vision | 3% (placebo 0%)1 | Not in the table2 | Not in the table3 | Not in the table4 |
Read the table with care. These are separate trials run in different men, with different designs and doses, so the label itself does not rank one drug against another. A drug that looks gentler in its own trial may simply have enrolled a different population. The numbers are best used to see the pattern: flushing is common with sildenafil and vardenafil, indigestion and back pain are more typical of tadalafil, and avanafil reports lower headache rates but at a lower overall efficacy in the network analyses below.
Does dose change side effects?
Yes, and clearly. In the fixed-dose sildenafil trials, headache was reported by 16% of men on 25 mg, 21% on 50 mg and 28% on 100 mg, flushing by 10%, 19% and 18%, and abnormal vision by 1%, 2% and 11%.1 Vardenafil's label likewise says some reactions, including headache, flushing and nausea, rose with dose over 5, 10 and 20 mg.3 The sildenafil label allows a dose of 25 mg to 100 mg, set by a clinician based on effectiveness and toleration.1 A lower dose is one way a prescriber may manage side effects, so raise them at follow-up rather than quitting.
What do the large comparisons say?
Network meta-analyses pool many trials to compare drugs that were rarely tested head to head. Their answers on tolerability are not identical.
| Analysis | Size | Tolerability finding |
|---|---|---|
| Yuan et al., 20136 | 118 trials, 31,195 men | No major difference in safety among the agents at recommended doses. |
| Chen et al., 20155 | 72 trials, 20,325 men in the adverse event analysis | At starting doses, sildenafil 50 mg had the highest overall adverse event rate and tadalafil 10 mg the lowest. Vardenafil 10 mg and avanafil 100 mg were similar to sildenafil 50 mg on adverse events, with lower efficacy. |
| Madeira et al., 20217 | 179 trials, 50,620 men | Sildenafil 100 mg was more related to visual disorders. Vardenafil and udenafil were more prone to cause nasal congestion. The authors judged avanafil hard to justify given its efficacy results. |
So the claim you will see on many telehealth pages, that one specific pill has the fewest side effects, rests on weak ground. The evidence supports narrower statements: tadalafil 10 mg looked best tolerated in one analysis, higher-dose sildenafil carries more visual effects, and no analysis shows any drug free of side effects.
What about the "10 times more potent" argument?
One reason often given for choosing vardenafil is that it is more potent than sildenafil, so a smaller dose is needed. Potency is not the same as tolerability. Vardenafil's label reports a headache rate of 15% and flushing of 11%, similar to or above the sildenafil flexible-dose figures, and the Chen analysis found vardenafil 10 mg had adverse event rates similar to sildenafil 50 mg.315 A smaller milligram dose does not by itself mean fewer side effects.
Which side effects mean stop and get help?
The common reactions above are bothersome but not dangerous. A few are different, and every one of these labels carries the same warnings:
- Sudden vision loss in one or both eyes. This could be a sign of non-arteritic anterior ischemic optic neuropathy (NAION). The labels advise caution in men with a history of NAION or a "crowded" optic disc.1234
- Sudden decrease or loss of hearing. Stop the medicine and seek prompt medical attention.1234
- An erection lasting more than four hours. The vardenafil label advises immediate medical help, and priapism that is not treated promptly can cause permanent damage to penile tissue.3
- Fainting or marked dizziness. Blood pressure can drop, particularly with alpha-blockers; the labels advise caution with that combination.13
Vardenafil also carries a QT warning: men with congenital QT syndrome or on class IA or III antiarrhythmic drugs should avoid it.3
Does side effect profile decide the right pill?
Only partly. The question that matters first is whether any ED tablet is appropriate for you. All four are contraindicated with nitrates, and the labels advise considering heart status before starting.134 Other factors include timing (tadalafil also has a once-daily label form),2 how often you expect to use it, and which other medicines you take. Our comparison of sildenafil, tadalafil and vardenafil covers those differences, and the guide to online prescriptions explains what a proper screening should ask.
Avoid "male enhancement" supplements sold as gentler alternatives. FDA warns that many are likely to contain hidden prescription ingredients, which means the side effects and the nitrate risk can exist with nothing on the label to say so.8 If you want to see how named services compare, start with the provider comparison.
What this article does not cover
This guide covers approved oral tablets. Compounded versions are not FDA-approved.9 The label tables are company-run trials and cannot rank the drugs against one another, and the network analyses combine trials of different designs and doses. A licensed clinician who knows your history should choose the drug and the dose.
Frequently asked questions
Which ED medication has the least side effects?
No head-to-head trial proves one tablet gentlest. A 2015 analysis found tadalafil 10 mg had the lowest overall adverse event rate at starting doses, while a 2013 analysis found no major safety difference among agents at recommended doses.
Is vardenafil easier to tolerate than sildenafil?
Not clearly. Vardenafil's label reports headache in 15% and flushing in 11% of men, and the 2015 analysis found vardenafil 10 mg had adverse event rates similar to sildenafil 50 mg.
Do lower doses cause fewer side effects?
Often, yes. Sildenafil's label shows headache and abnormal vision rates rising from the 25 mg to the 100 mg dose, and vardenafil's label reports dose-related increases in several reactions.
Which ED side effects need emergency care?
An erection lasting more than four hours, sudden loss of vision in one or both eyes, and sudden decrease or loss of hearing. The labels tell patients to seek prompt medical attention.
Are over-the-counter ED supplements gentler?
No. FDA warns that many male enhancement products are likely to contain hidden prescription ingredients, so side effects and nitrate interactions can occur without being labeled.
Related reading
Sources
- Pfizer. VIAGRA (sildenafil citrate) prescribing information. DailyMed, U.S. National Library of Medicine.
- Eli Lilly. CIALIS (tadalafil) prescribing information. DailyMed, U.S. National Library of Medicine.
- Teva Pharmaceuticals USA. Vardenafil hydrochloride tablets prescribing information. DailyMed, U.S. National Library of Medicine.
- Metuchen Pharmaceuticals. STENDRA (avanafil) prescribing information. DailyMed, U.S. National Library of Medicine.
- Chen L, et al. Phosphodiesterase 5 inhibitors for the treatment of erectile dysfunction: a trade-off network meta-analysis. Eur Urol. 2015. PubMed 25817916.
- Yuan J, et al. Comparative effectiveness and safety of oral phosphodiesterase type 5 inhibitors for erectile dysfunction: a systematic review and network meta-analysis. Eur Urol. 2013. PubMed 23395275.
- Madeira CR, et al. Efficacy and safety of oral phosphodiesterase 5 inhibitors for erectile dysfunction: a network meta-analysis and multicriteria decision analysis. World J Urol. 2021. PubMed 32388784.
- U.S. Food and Drug Administration. Sexual Enhancement and Energy Product Notifications.
- U.S. Food and Drug Administration. Compounding and the FDA: Questions and Answers.