What is Sildenafil?
What is Sildenafil (Viagra)?
Sildenafil, commonly known by its brand name Viagra, is a prescription medication used to treat erectile dysfunction (ED) in adult men. It belongs to a class of medications known as phosphodiesterase type 5 (PDE5) inhibitors. This drug helps men achieve and maintain an erection by increasing blood flow to the penis during sexual stimulation.
What is Sildenafil (Viagra) Used For?
- Erectile Dysfunction (ED) or Impotence
- Pulmonary Arterial Hypertension (under the name Revatio)
How Sildenafil (Viagra) Works?
Sildenafil blocks the PDE5 enzyme, which normally breaks down a substance called cyclic GMP. Cyclic GMP relaxes the smooth muscles and allows blood to flow into the penis. By preserving this compound, sildenafil makes it easier to get and keep an erection in response to sexual arousal.
When Does Sildenafil (Viagra) Start Working?
| Time After Taking | Effect |
| 30 minutes | Possible early effects begin |
| 1 hour (typical) | Peak effectiveness |
| 4 hours | Reduced effect window |
You should take sildenafil on an as-needed basis about 30 minutes to 1 hour before sexual activity. It can be taken up to 4 hours in advance. Avoid taking it more than once in 24 hours.
| Drug Facts | |
|---|---|
| Brand Name | Viagra |
| Generic Name | Sildenafil |
| Drug Class | PDE5 Inhibitor |
| Controlled Substance | No |
| Generic Status | Lower-cost generic |
| Availability | Prescription only |
Generic Status: Available as a lower-cost generic
Side Effects of Sildenafil (Viagra)
Common Side Effects (may improve over time)
- Headache (16%–28%)
- Flushing (10%–19%)
- Indigestion (3%–17%)
- Vision changes or sensitivity to light (1%–11%)
- Nasal congestion (4%–9%)
Other Reported Effects:
- Dizziness
- Back or muscle pain
- Rash
- Nausea
Serious Side Effects (Seek immediate care):
- Erection lasting longer than 4 hours (priapism)
- Sudden vision loss
- Sudden hearing loss
- Very low blood pressure
Who Should Avoid Sildenafil (Viagra)?
Sildenafil may not be safe for everyone. The drug is contraindicated in certain conditions:
| Contraindication | Why It Matters |
| Taking nitrates (e.g., nitroglycerin) | Can cause dangerous blood pressure drop |
| Severe heart conditions or recent stroke/heart attack | Risk with sexual activity and drug side effects |
| Known allergy to sildenafil | May trigger allergic reaction |
| Retinitis pigmentosa | May increase risk of vision problems |
Pharmacist Tips for Safe Use
- Take sildenafil on an empty stomach for faster onset
- Do not use more than one dose per day
- Avoid alcohol and high-fat meals around the time of taking it
- If you have heart or blood pressure conditions, consult your provider before using
- Use condoms—sildenafil does not prevent STDs
Pros and Cons of Sildenafil (Viagra)
✔ Pros
- Effective for ED in most men
- Taken only when needed
- Works within 30–60 minutes
- Available as a generic (affordable)
- Multiple strengths available
✘ Cons
- Not safe with nitrates or some heart meds
- May cause headaches or flushing
- Less effective after high-fat meals
- Requires timing and planning before sex
- Cannot be taken more than once per day
Drug Interactions
Always inform your doctor about other medications or supplements you’re taking. Sildenafil has notable interactions with:
- Nitrates (e.g., isosorbide, nitroglycerin)
- Alpha-blockers (e.g., tamsulosin)
- Antifungals (e.g., ketoconazole)
- Antivirals (e.g., ritonavir)
- Blood pressure medications
These can increase the risk of low blood pressure or other side effects.
How People Use Sildenafil (Viagra)
| Usage Pattern | Percentage |
| Took for 10+ years | 89% |
| Discontinued due to expense | 39% |
| Discontinued due to ineffectiveness | 27% |
| Discontinued by doctor | 9% |
Frequently Asked Questions
Q: How long does sildenafil last?
A: Effects typically last 4–6 hours, although this varies by individual.
Q: Can women take sildenafil?
A: Sildenafil is not FDA-approved for use in women for sexual dysfunction.
Q: What if I don’t have ED? Can I still take it?
A: No. Taking sildenafil without ED may cause harmful side effects and is not recommended.
Q: Will sildenafil cause an automatic erection?
A: No. Sexual stimulation is required for sildenafil to work.
Bottom Line
Sildenafil (Viagra) is one of the most commonly prescribed medications for erectile dysfunction. It’s effective, fast-acting, and relatively safe when used correctly. However, it’s not right for everyone. Always speak to your healthcare provider to determine if sildenafil is appropriate based on your health conditions and medications.
