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hormonePrescription testosterone replacement for men with confirmed low testosterone.
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No. 055medication
Sildenafil
Sildenafil is a medication that is FDA-approved, prescription only.
Also known as Viagra, Revatio, generic Viagra
Sildenafil is a PDE5 inhibitor that helps the penis fill with blood during sexual arousal. Viagra was the first pill approved for erectile dysfunction, and the same drug is approved under another name (Revatio) for pulmonary arterial hypertension.
Is Sildenafil FDA-approved?
Approved by the FDA. A licensed clinician has to decide it is right for you and prescribe it. Viagra was FDA-approved in 1998 for erectile dysfunction; Revatio was approved in 2005 for pulmonary arterial hypertension. FDA-approved generics exist. Prescription only in the US, unlike the UK, where regulators reclassified a pharmacy version (Viagra Connect) as non-prescription in 2017.
As of October 7, 2026.
Key takeaways
- Sildenafil (Viagra) was the first FDA-approved pill for erectile dysfunction, in 1998, and is now widely available as a generic.
- It only works with sexual stimulation, and blood levels peak about an hour after it is taken.
- Headache, flushing, indigestion and short-lived vision changes are the most common side effects.
- It needs a prescription in the US and must never be combined with nitrates.
How does Sildenafil work?
Sexual arousal releases nitric oxide, which raises a messenger called cGMP that relaxes blood vessels in the penis so it can fill with blood. The enzyme PDE5 breaks cGMP down. Sildenafil blocks PDE5, so the natural signal lasts longer.
The Viagra label says it has no effect without sexual stimulation. The same action in lung blood vessels is why sildenafil is also approved, as Revatio, for pulmonary arterial hypertension.
Can you buy sildenafil over the counter?
Not in the US. Drugs@FDA lists Viagra and its generics as prescription drugs. Drugs@FDA: Viagra, NDA 020895
In the UK, the MHRA reclassified Viagra Connect as a pharmacy medicine in 2017, sold after a conversation with a pharmacist. That change does not apply to the US. MHRA (Nov 2017): Viagra Connect reclassified to a pharmacy medicine in the UK
FDA warns that many sexual enhancement products sold online, in stores and at gas stations contain hidden sildenafil or tadalafil and are dangerous with nitrates. A product missing from FDA's list is not proof it is safe. FDA: Sexual enhancement and energy product notifications (hidden ingredients)
Does insurance cover sildenafil?
Medicare's Part D manual excludes drugs when used for sexual or erectile dysfunction, but the same drugs count as Part D drugs when prescribed for another FDA-approved use such as pulmonary hypertension. CMS: Medicare Prescription Drug Benefit Manual, Chapter 6 (Part D drugs and formulary requirements)
FDA has approved several generic versions of Viagra and of Revatio, so many people pay cash at a pharmacy or through telehealth instead of using insurance. Drugs@FDA: Revatio, NDA 021845
What does the evidence say about Sildenafil?
Strong human evidenceRandomized trials since 1998 and a 2021 network meta-analysis of 179 trials show sildenafil improves erections compared with placebo.
What to expect
What trials and prescribing information measured over time. Everyone responds differently.
- 30 to 120 minutes
The Viagra label says blood levels peak within 30 to 120 minutes, with a median of about an hour.
- Up to about 4 hours
The label allows use from 30 minutes to 4 hours before sexual activity. It only works with sexual stimulation.
- Over several tries
The AUA notes more than one try may be needed before deciding whether it works.
What do clinicians say about Sildenafil?
Sildenafil is one of the best-studied drugs in urology. Guidelines treat it as a standard option once heart health and medicines have been checked.
The AUA guideline says men with erectile dysfunction should be told about FDA-approved PDE5 inhibitors, with their benefits and risks, unless they are contraindicated.
American Urological Association: Erectile Dysfunction guideline (2018)The AUA notes the PDE5 inhibitors differ in how fast they start, how long they last and whether food limits them, and that more than one try may be needed to judge the effect.
American Urological Association: Erectile Dysfunction guideline (2018)In the 1998 NEJM trial that led to approval, 69% of attempts at intercourse were successful with sildenafil compared with 22% with placebo.
Goldstein et al.: Oral sildenafil in the treatment of erectile dysfunction (NEJM 1998)The Viagra label contraindicates use with nitrates or riociguat and warns about sudden vision loss, sudden hearing loss, prolonged erections and low blood pressure with alpha blockers.
DailyMed: Viagra (sildenafil) prescribing informationA 2021 network meta-analysis of 179 randomized trials concluded sildenafil and tadalafil should be the first options considered.
Oral PDE5 inhibitors for erectile dysfunction: network meta-analysis and multicriteria decision analysis (World J Urol 2021)
Summaries of published guidelines, drug labels, regulators and reviews, each attributed to its source. DiscoverMedica does not employ clinicians.
Is Sildenafil right for you, and who should avoid it?
Often considered for
- Adult men with erectile dysfunction who do not take nitrates
- Men who want an option taken shortly before sex rather than one with a long window
- Adults with pulmonary arterial hypertension, under the Revatio name and a specialist's care
Not a fit, or needs extra care
- Anyone taking nitrates in any form, or riociguat
- Men advised against sexual activity because of heart disease
- People taking strong CYP3A4 inhibitors such as some HIV antivirals, unless the prescriber has planned for it
- Women: the label says it is not indicated for females
Only a licensed clinician who knows your history can decide whether it is right for you.
What are the risks and side effects of Sildenafil?
- Never combine it with nitrates or riociguat, because blood pressure can drop dangerously.
- Common side effects on the label are headache, flushing, indigestion, vision changes (a blue tinge or blur), nasal congestion and back pain.
- Seek care for an erection lasting over 4 hours, sudden vision loss or sudden hearing loss.
- Alpha blockers and other blood pressure drugs can add to its blood-pressure-lowering effect; some antivirals and antifungals raise its levels sharply.
What should you ask a clinician about Sildenafil?
- Is my heart healthy enough for sexual activity and a PDE5 inhibitor?
- Would sildenafil or tadalafil suit how I live better?
- Do any of my medicines interact with it?
These save with the compound when you add it to My Journal, so they’re on the printout for your visit.
How do people get Sildenafil through telehealth?
Answer an online questionnaire about symptoms, heart health, blood pressure and medicines.
A licensed clinician reviews it and prescribes if it is safe for you.
Generic sildenafil ships discreetly, or the prescription goes to your local pharmacy.
Message the clinician if it does not work or causes side effects; switching to tadalafil is a common next step.
What programs often include
- Clinician review and prescription
- Ongoing messaging with the care team
- Discreet shipping on a refill schedule
How some providers do it
- HimsLists generic sildenafil, sildenafil chews and brand Viagra after an online visit with a provider.
- RoLists generic sildenafil and brand Viagra on a monthly plan after an online consultation.
- KeepsLists sildenafil citrate (generic Viagra) after a provider consultation.
- Amazon PharmacyFills generic sildenafil from your own prescriber.
From each provider’s own site, checked October 7, 2026. Programs change, so confirm the details before you sign up.
Where can I get Sildenafil?
14 providers list Sildenafil on DiscoverMedica, lowest listed price first.
Starting at $2/pilllisted price†
Start at Lemonaid Health Starting at $2 per tabletlisted price†
Start at Rex MD From $22/molisted price†
Start at Hims $40/molisted price†
Start at Hone Health Starting at $49.99/molisted price†
Start at Maximus $79 per orderlisted price†
Start at Winona see site
Start at Amazon Pharmacy BlueChewBlueChew SIL compounded sildenafil chewable
Compounded, not FDA-approvedClinician consult required
see site
Start at BlueChew see site
Start at Evernow Mark Cuban Cost Plus DrugsSildenafil citrate tablet (generic Revatio/Viagra)
Clinician consult required
see site
Start at Mark Cuban Cost Plus Drugs † Prices as listed by the provider when we checked; they change.
How much does Sildenafil cost?
Listed prices run from $22 to $49.99 a month across 4 providers, as checked October 7, 2026.
Prices as listed by the provider when we checked; they change. Membership or consult fees may be separate; see each provider.
Sildenafil: questions, answered
What are the side effects of sildenafil?
In the Viagra label trials, the most common were headache, flushing, indigestion, abnormal vision such as a blue tinge or blurring, nasal congestion, back pain and muscle aches. Rare but urgent problems include an erection lasting over 4 hours, sudden vision loss and sudden hearing loss. Combining it with nitrates can cause a dangerous drop in blood pressure.
Is sildenafil the same as Viagra?
Yes. Sildenafil is the active ingredient in Viagra, first approved by FDA in 1998, and FDA has approved several generic versions it rates as equivalent. Revatio is sildenafil too, but it is approved for pulmonary arterial hypertension rather than erectile dysfunction, and is prescribed by specialists for that use.
Can I get Viagra over the counter in the US?
No. Sildenafil is prescription only in the US. The UK made a pharmacy version, Viagra Connect, available after a pharmacist conversation in 2017, but that does not apply here. FDA warns that many "herbal" sexual enhancement products sold without a prescription secretly contain sildenafil or tadalafil, which is dangerous for people on nitrates.
How long does sildenafil take to work?
The Viagra label says blood levels peak between 30 and 120 minutes after it is taken, with a median around one hour. It does not cause an erection by itself; sexual stimulation is still needed. The AUA notes it may take more than one try to judge whether it works.
Does Medicare cover sildenafil?
Medicare Part D excludes drugs used only for erectile dysfunction under CMS rules. When sildenafil is prescribed for an FDA-approved use outside sexual dysfunction, such as pulmonary arterial hypertension, it can count as a Part D drug. Generic sildenafil is widely available, so many people with ED pay cash through a pharmacy or telehealth service.
Can women take sildenafil?
The Viagra label states that it is not indicated for use in females. Its approved uses are erectile dysfunction in men and, as Revatio, pulmonary arterial hypertension in adults. Women with low desire or arousal concerns should talk with a clinician about the causes and the treatments that have actually been studied and approved for women.
Important safety information
Key risks
- Never combine it with nitrates or riociguat, because blood pressure can drop dangerously.
- Common side effects on the label are headache, flushing, indigestion, vision changes (a blue tinge or blur), nasal congestion and back pain.
- Seek care for an erection lasting over 4 hours, sudden vision loss or sudden hearing loss.
- Alpha blockers and other blood pressure drugs can add to its blood-pressure-lowering effect; some antivirals and antifungals raise its levels sharply.
Talk to a clinician first, or avoid it, if
- Anyone taking nitrates in any form, or riociguat
- Men advised against sexual activity because of heart disease
- People taking strong CYP3A4 inhibitors such as some HIV antivirals, unless the prescriber has planned for it
- Women: the label says it is not indicated for females
This is not a complete list of risks. Read the full prescribing information and any Medication Guide, and talk to a licensed clinician or pharmacist about your own situation. If you have a severe reaction, call 911. You can report side effects to the FDA through MedWatch at 1-800-FDA-1088.
Sources
- DailyMed: Viagra (sildenafil) prescribing information
- Drugs@FDA: Viagra, NDA 020895
- Goldstein et al.: Oral sildenafil in the treatment of erectile dysfunction (NEJM 1998)
- Oral PDE5 inhibitors for erectile dysfunction: network meta-analysis (World J Urol 2021)
Also checked for this guide
- Drugs@FDA: Revatio, NDA 021845
- American Urological Association: Erectile Dysfunction guideline (2018)
- CMS: Medicare Prescription Drug Benefit Manual, Chapter 6 (Part D drugs and formulary requirements)
- FDA: Sexual enhancement and energy product notifications (hidden ingredients)
- MHRA (Nov 2017): Viagra Connect reclassified to a pharmacy medicine in the UK
Guide reviewed October 7, 2026.
Educational information only, not medical advice. It does not replace a conversation with a licensed clinician.
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