At a Glance: What Viagra Is

Active ingredient: Sildenafil (as sildenafil citrate). Viagra is a prescription medicine used mainly to treat erectile dysfunction in adult men. It can also be prescribed for pulmonary arterial hypertension under different brand names or strengths.

Available oral strengths in the U.S. marketplace commonly include:

  • 50 mg
  • 25 mg
  • 100 mg

Looking for dosing details? Jump to Dosage and Directions. For a discussion of alternatives and pricing, see Alternatives and Prices in the USA.

How Viagra Works

Viagra belongs to a group of medicines called PDE5 inhibitors. During sexual stimulation, the body releases nitric oxide in the penis. Sildenafil strengthens this natural signal, supporting smooth muscle relaxation and improving blood flow into erectile tissue. The result is improved erectile function when sexual arousal is present.

Viagra does not increase sexual desire and will not trigger an erection without sexual stimulation.

For information about substances that may alter how sildenafil works, see Drug and Food Interactions.

Dosage and Directions

The commonly prescribed starting dose for erectile dysfunction is 50 mg taken about 30 to 60 minutes before sexual activity. Your clinician may adjust the dose to 25 mg or 100 mg based on effectiveness and tolerability. Do not take more than one dose in a 24-hour period.

  • Taking Viagra with a high-fat meal can delay onset of effect.
  • Avoid grapefruit and grapefruit juice, which can raise sildenafil levels.
  • Swallow tablets with water; take only as needed, not on a fixed daily schedule unless specifically directed by your prescriber.

Older adults or people with certain medical conditions may need lower doses. For safety factors, review Precautions and Contraindications.

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Precautions and Warnings

Tell your clinician if you have allergies to sildenafil or any tablet component. Some individuals, particularly older adults, can be more sensitive to side effects like dizziness or blood pressure changes.

  • Use caution if you have heart disease, recent stroke or heart attack, arrhythmias, or low blood pressure.
  • Seek medical advice if you have anatomical deformation of the penis or conditions predisposing to priapism.
  • Visual or hearing changes require immediate medical attention.

For sport-related use, sildenafil is not approved to enhance performance. See Legal and Regulatory Notes for details on sports and policy considerations in the USA.

Who Should Not Use Viagra

Do not take Viagra if any of the following apply to you:

  • You use nitrates (for example, nitroglycerin) for chest pain or heart problems.
  • You take riociguat or other guanylate cyclase stimulators.
  • You are using another treatment for erectile dysfunction at the same time unless your prescriber specifically directs a switch.
  • You have a known hypersensitivity to sildenafil or any ingredient in the tablet.
  • It is not for women or for individuals under 18 years of age for ED use.

Questions about interacting medicines? Jump to Interactions.

Possible Side Effects

Many users experience only mild and short-lived effects. Common reactions can include:

  • Headache
  • Flushing or warmth
  • Dyspepsia or heartburn
  • Nasal congestion
  • Dizziness or lightheadedness
  • Diarrhea

Seek urgent care if you develop severe chest pain, fainting, an allergic reaction (rash, swelling, trouble breathing), sudden vision or hearing loss, or an erection lasting longer than 4 hours (priapism).

If you notice any effects not listed here, contact your doctor or pharmacist.

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Drug and Food Interactions

Important interactions may increase side effects or reduce effectiveness. Avoid or carefully review the following with your clinician:

  • Nitrates and recreational nitrites such as amyl or butyl nitrite (poppers) due to dangerous blood pressure drops.
  • Alpha-blockers and certain blood pressure medicines, which can further lower blood pressure.
  • Other PDE5 inhibitors or ED medications taken concurrently.
  • Strong CYP3A4 inhibitors or inducers that can alter sildenafil levels (for example, some antifungals, macrolide antibiotics, HIV protease inhibitors, certain seizure medicines).
  • Grapefruit products, which can raise drug exposure.

Always provide your pharmacist and prescriber with a current medication list, including supplements and over-the-counter products.

Missed Dose

Viagra is taken as needed for sexual activity, so there is no routine dosing schedule. If you forget a planned dose, take it when appropriate before sexual activity, but never double up or exceed one dose per day.

Overdose

If too much sildenafil is taken, call emergency services or seek urgent medical attention. Symptoms can include chest pain, pronounced dizziness, fainting, a racing or irregular heartbeat, and nausea.

Poison control in the USA: 1-800-222-1222.

Storage and Handling

  • Store at 20 to 25 C (68 to 77 F).
  • Keep tablets away from moisture and direct light.
  • Do not store in the bathroom.
  • Keep out of reach of children and pets.

Dispose of unused tablets according to local take-back programs when available.

Alternatives and Similar Medicines

If Viagra is not suitable or not effective, clinicians may consider other PDE5 inhibitors or approaches. Options include:

  • Avanafil (brand Stendra) - typically faster onset for some users.
  • Tadalafil (brand Cialis) - longer duration; can be taken daily at low dose for continuous effect.
  • Vardenafil (brand Levitra) - similar duration to sildenafil; formulations may vary.
  • Generic sildenafil - same active ingredient as Viagra, often at a lower cost.

Non-pill options for ED may include vacuum erection devices, urethral suppositories, penile injections, psychotherapy for psychogenic components, and lifestyle measures such as exercise, sleep optimization, smoking cessation, and cardiometabolic risk control.

Compare typical USA pricing below: Prices in the USA.

Typical Prices in the USA (Approximate, cash pay)

Prices vary widely by pharmacy, dose, quantity, and discount programs. The ranges below are rough estimates per tablet in USD.

  • Viagra brand 25-100 mg: around $70 to $90 per tablet.
  • Generic sildenafil 25-100 mg: about $0.50 to $5 per tablet, sometimes up to $10 depending on pharmacy and pack size.
  • Tadalafil brand (Cialis) 5-20 mg: roughly $70 to $90 per tablet; generic tadalafil often $0.80 to $6.
  • Vardenafil (Levitra) brand availability varies; generics often $2 to $10 per tablet.
  • Avanafil (Stendra) 50-200 mg: commonly $20 to $70 per tablet.

Example scenario: 4 tablets of brand Viagra may cost about $280 to $360 total; 8 tablets of generic sildenafil may cost about $4 to $40 total depending on pharmacy and discounts.

Insurance and manufacturer coupons may change out-of-pocket costs. For safe online buying guidance, see Legal and Regulatory Notes.