Key Takeaways
- Sildenafil and tadalafil each help men get and keep an erection firm enough for sex. They work with arousal, not in place of it.
- Both were approved for erectile dysfunction more than 20 years ago. Tadalafil is also approved for the signs and symptoms of an enlarged prostate.
- Tadalafil can be taken once a day, so you don't have to time each dose around sex.
- Double Powered pairs the two in one prescription, mixed for you by a licensed pharmacy at the strength your provider sets.
- Your provider checks your health history and every medicine you take before prescribing, and looks at your plan again before every refill.
It's common for erections to be less firm or less reliable than you'd like. Between 30 million and 50 million men in the United States have erectile dysfunction, and it becomes more common with age. Two prescription medicines, sildenafil and tadalafil, can help, and each has its own approved label.
How Sildenafil and Tadalafil Can Help
Both help you get and keep an erection firm enough for sex, working with your body's natural response to arousal. During sexual stimulation, your body releases nitric oxide in the erectile tissue of the penis, which raises a signaling molecule called cyclic GMP. That relaxes smooth muscle so more blood can flow in. Sildenafil and tadalafil both block PDE5, the enzyme that breaks cyclic GMP back down, which is why they're called PDE5 inhibitors.
Sildenafil
Sildenafil was approved in 1998 for erectile dysfunction, and you take it as needed, ahead of sex. In a 12-week study, men taking sildenafil had successful sex in 69% of attempts during the final four weeks of treatment.
Tadalafil
Tadalafil was approved in 2003 for erectile dysfunction. It's also approved for the signs and symptoms of benign prostatic hyperplasia (an enlarged prostate), and for the two together. Its label covers two ways to take it: as needed or once a day. In its approved tablet form, as-needed tadalafil improved erectile function compared with placebo for up to 36 hours after a dose.
81% of men said their erections improved after 12 weeks of taking tadalafil 20 mg as needed. If you take it daily, you don't have to time a dose around sex. In another study, 84.5% of men taking tadalafil 5 mg daily said their erections improved after 12 weeks.
| Sildenafil | Tadalafil | |
|---|---|---|
| Approved uses | Erectile dysfunction | Erectile dysfunction; the signs and symptoms of benign prostatic hyperplasia; both together |
| How it's taken | As needed, ahead of sexual activity | As needed, ahead of sexual activity, or once a day with no need to time it around sex |
How the Two Are Used Together
Double Powered combines sildenafil and tadalafil in one compounded prescription. A licensed pharmacy mixes it for you, and your provider chooses the strength and quantity after reviewing your health history. It comes in 6-dose, 10-dose and 12-dose packs, with instructions for use.
The pairing doesn't have an approved label of its own.† Your provider decides whether it fits you. If one medicine suits you better, Daily Boost is a 28-dose pack of tadalafil for daily use, and LIV's other formulas range from one to four active ingredients.
WHAT HAS A LABEL
The warning does not go away with the label.
- Sildenafil Erectile dysfunction Contraindicated with nitrates and with guanylate cyclase stimulators
- Tadalafil Erectile dysfunction; signs and symptoms of BPH Contraindicated with nitrates and with guanylate cyclase stimulators
- The two together No approved label Contraindicated with nitrates and with guanylate cyclase stimulators
Two labels, one preparation, and the warnings remain.
Your Evaluation and What to Tell Your Provider
Your provider starts by getting the full picture: your health history and every medicine you take. Then they decide with you whether treatment is right for you. The approved sildenafil labeling says your evaluation should also look for possible underlying causes. That's good for your overall health too, since NIDDK links erectile dysfunction with conditions such as diabetes, heart disease and obesity. Our guide to the clinician evaluation explains what to expect.
Headache and flushing are among the most common side effects listed on both labels. Make sure your provider knows about any nitrate for chest pain, because nitrates aren't used with either medicine.
Make the Most of Your First Visit
Bring a list of your medicines, including anything for chest pain, blood pressure or an enlarged prostate, and anything you take without a prescription. Share what has changed with your erections, and when you first noticed it. You might ask:
- Whether one medicine or the pairing is a better fit for you
- How to time your doses
- What to watch for
When you're ready, start with a short online evaluation. A licensed provider reviews it and decides with you whether treatment fits and which formula suits you.
Frequently Asked Questions
What did studies of sildenafil and tadalafil find?
In a randomized 12-week trial of 329 men with erection difficulties, 69% of attempts at sex were successful with sildenafil in the last four weeks, compared with 22% on placebo. Doses went up to 100 mg, and the figure counts attempts, not men.
In five randomized 12-week trials of 1,112 men with erection difficulties, 81% of men taking tadalafil 20 mg as needed reported improved erections, compared with 35% on placebo. In a randomized 12-week trial of 268 men, 84.5% of those taking tadalafil 5 mg daily reported improved erections, compared with 28.3% on placebo; that was a secondary, patient-reported measure, and Daily Boost wasn't the study product.
These are different studies with different measures, so they don't compare the two medicines, and they don't show what the combination does. Each tested an oral medicine on its own, not a compounded pairing or your prescribed strength. Study doses aren't instructions for use, and results vary.
Can you take sildenafil and tadalafil at the same time?
Not on your own. Each approved label says the safety and effectiveness of combining it with other PDE5 inhibitors or other erectile dysfunction treatments haven't been studied. The sildenafil label adds that such combinations may lower blood pressure further and aren't recommended, and the tadalafil label asks prescribers to tell patients not to take it with other PDE5 inhibitors. A pairing like Double Powered is compounded and used off-label, against that label guidance. Whether it's right for you is your provider's call, based on your history. Never add another erection medicine yourself.
What does compounded mean for my prescription?
A licensed pharmacy mixes your medicine for you, to the prescription your provider writes. Compounded medicines aren't FDA-approved, and the FDA doesn't review their safety, effectiveness or quality before they're marketed. A compounded pairing isn't a generic of a brand-name pill, because there's no approved two-medicine product for it to copy. It has no FDA-approved prescribing information of its own, so follow your provider's instructions and the directions that come with your prescription.
Why does my provider ask about nitrates?
Nitrates, such as nitroglycerin for chest pain, aren't taken with sildenafil or tadalafil in any form, whether regularly or only now and then. Both approved labels list them as a contraindication, because these medicines can make the drop in blood pressure that nitrates cause stronger. The same goes for guanylate cyclase stimulators such as riociguat. Tell your provider about alpha-blockers and other blood pressure medicines too, since together they can lower blood pressure further, sometimes enough to cause dizziness or fainting. Also mention any version of either medicine prescribed for high blood pressure in the lungs.
Who shouldn't take sildenafil or tadalafil?
Your provider reviews your history first. The labels say these medicines aren't for anyone taking a nitrate or a guanylate cyclase stimulator, or anyone with a known allergy to sildenafil or tadalafil. The sildenafil label adds that erection treatments generally shouldn't be used by men whose heart health makes sexual activity inadvisable. It also notes that controlled data don't exist for some groups, including men with a recent heart attack or stroke, or with unstable angina.
What side effects can sildenafil and tadalafil cause?
Side effects reported in at least 2% of people in the sildenafil label include headache, flushing, indigestion, abnormal vision, nasal congestion, back pain, muscle aches, nausea, dizziness and rash. The tadalafil label lists headache, indigestion, back pain, muscle aches, nasal congestion, flushing and pain in a limb.
Stop taking them and get medical help right away for a sudden loss of vision in one or both eyes. It can be a sign of a rare condition called NAION that can reduce vision, sometimes permanently. Do the same for a sudden decrease or loss of hearing, which may come with ringing in the ears or dizziness. Neither medicine protects against sexually transmitted diseases.
What happens if an erection lasts more than four hours?
Get medical help right away. The approved sildenafil labeling says to seek immediate medical help for an erection that lasts longer than four hours. If priapism (a painful erection lasting more than six hours) isn't treated right away, it could cause lasting harm to penile tissue and permanent loss of potency.
Does taking both work better than one alone?
Neither label shows that it does. Both say combining them hasn't been studied, so neither supports calling the pairing stronger, faster or longer-lasting than either medicine alone. Your provider selects your formula and strength after reviewing your health history, whether that's one medicine or two.
Do you need a prescription for this?
Yes. Both are prescription medicines, and a licensed provider reviews your health history before prescribing. The FDA also warns about sexual enhancement products sold as supplements that turn out to contain hidden drug ingredients, which matters most if you take a nitrate.
References
Brock, G. B., McMahon, C. G., Chen, K. K., Costigan, T., Shen, W., Watkins, V., Anglin, G., & Whitaker, S. (2002). Efficacy and safety of tadalafil for the treatment of erectile dysfunction: Results of integrated analyses. Journal of Urology, 168(4 Pt 1), 1332-1336. https://pubmed.ncbi.nlm.nih.gov/12352386/
Eli Lilly and Company. (2026). CIALIS (tadalafil) tablets, for oral use [Prescribing information]. DailyMed, U.S. National Library of Medicine. SPL set id bcd8f8ab-81a2-4891-83db-24a0b0e25895, effective June 3, 2026, SPL version 52. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895
Goldstein, I., Lue, T. F., Padma-Nathan, H., Rosen, R. C., Steers, W. D., & Wicker, P. A. (1998). Oral sildenafil in the treatment of erectile dysfunction. New England Journal of Medicine, 338(20), 1397-1404. https://pubmed.ncbi.nlm.nih.gov/9580646/
National Institute of Diabetes and Digestive and Kidney Diseases. (2024). Definition & facts for erectile dysfunction. National Institutes of Health. https://www.niddk.nih.gov/health-information/urologic-diseases/erectile-dysfunction/definition-facts
Porst, H., Giuliano, F., Glina, S., Ralph, D., Casabé, A. R., Elion-Mboussa, A., Shen, W., & Whitaker, J. S. (2006). Evaluation of the efficacy and safety of once-a-day dosing of tadalafil 5mg and 10mg in the treatment of erectile dysfunction: Results of a multicenter, randomized, double-blind, placebo-controlled trial. European Urology, 50(2), 351-359. https://pubmed.ncbi.nlm.nih.gov/16766116/
U.S. Food and Drug Administration. (2025). Compounding and the FDA: Questions and answers. Content current as of September 16, 2025. https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers
U.S. Food and Drug Administration. (2026). Sexual enhancement and energy product notifications. Content current as of July 23, 2026. https://www.fda.gov/drugs/medication-health-fraud/tainted-sexual-enhancement-products
Viatris Specialty LLC. (2026). VIAGRA (sildenafil citrate) tablets, for oral use [Prescribing information]. DailyMed, U.S. National Library of Medicine. SPL set id d905dc8d-917f-4ea3-a4ee-a1ecf6967d4e, version 6, published February 13, 2026; re-verified August 19, 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d905dc8d-917f-4ea3-a4ee-a1ecf6967d4e
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