Sildenafil and tadalafil are the two generic ED medications that work. Both are PDE5 inhibitors — they block the enzyme that breaks down cGMP, allowing increased blood flow that produces erections when sexually stimulated. They do not cause erections without arousal.

The patents on both have expired. Generic versions cost a fraction of brand-name Viagra and Cialis. And the differences between them are practical, not marketing.

The clinical difference

Sildenafil (generic Viagra): Takes 30–60 minutes to work, lasts 4–6 hours. More affected by food — a high-fat meal can delay onset by 60–90 minutes. Works with sexual stimulation, not without.

Tadalafil (generic Cialis): Takes 1–2 hours to work but lasts 36 hours ("the weekend pill"). Also available as a daily low-dose version (2.5–5mg daily) that maintains a constant blood level for spontaneous use without timing.

The practical difference: if you prefer to take a pill and have a specific window of activity, sildenafil is fine and cheaper per dose. If you want spontaneous activity without timing a pill, tadalafil — especially daily dosing — removes the planning requirement.

What each costs online

Sildenafil generic online starts at $17/month at Hims for a 4-tablet supply (about 1 dose per week). BlueChew offers sildenafil chewable tablets starting at $20/month. Both require a prescription via a 5-10 minute online consultation.

Tadalafil daily dosing runs $20–45/month online. The daily low dose (5mg) is typically more expensive than as-needed sildenafil but eliminates the timing issue entirely.

Both generics are available through Hims, Ro, BlueChew, Keeps, Sesame Care, and most men's health telehealth platforms. The consultation process is almost identical across all of them — a short questionnaire about health history, a physician review, and same-day prescription approval if you are not on nitrates.

The nitrate warning

The one hard contraindication for both drugs: nitrate medications used for heart conditions (nitroglycerin, isosorbide). Combining PDE5 inhibitors with nitrates causes dangerous blood pressure drops. Every legitimate platform screens for this. Do not use any source that does not ask about nitrate use.

Which to choose

For planned activity, sildenafil at $17/month is the most cost-effective option. For spontaneous activity or if timing a pill feels like a disruption, tadalafil daily at $20–45/month is worth the premium. Both are safe, both work, both are generic versions of drugs with decades of human safety data.