Treatment Options
PDE5 Inhibitors: Sildenafil, Tadalafil & Beyond
The most common first-line treatment for ED — effective for most men, simple to take, with a long safety record. Here's how they work and how to choose between them.
The class includes sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra/Staxyn), and avanafil (Stendra). All four work the same way — the differences that matter are timing and duration, not potency. That's what most of the choice between them comes down to.
How they work — and the one thing everyone should know
These drugs block the PDE5 enzyme, protecting the chemical signal that lets penile blood vessels relax and fill. The crucial point: they do not create desire or cause an automatic erection. You still need to be sexually aroused for them to work. Men who think a pill 'didn't work' have often taken it without enough stimulation, on a full stomach, or without giving it enough time.
- Never combine any PDE5 inhibitor with nitrate medications (such as nitroglycerin for chest pain) or with the recreational drugs known as 'poppers' (amyl/butyl nitrite). The combination can cause a sudden, dangerous drop in blood pressure.
- Tell your doctor about every medication you take, and seek emergency care for an erection lasting over 4 hours.
Sildenafil vs. tadalafil
Most real-world choices come down to these two. They're equally effective on average; they differ in timing, food sensitivity, and side-effect feel. The 'best' one is the one that fits how you live.
Sildenafil (Viagra)
- Onset
- 30–60 minutes
- Duration
- 4–6 hours
- Food
- Best on an empty stomach; fatty meals delay it
- Dosing
- On-demand only
- Max dose
- 100 mg
- Side effects
- Headache, flushing, occasional bluish vision tint
Tadalafil (Cialis)
- Onset
- 30 minutes–2 hours
- Duration
- Up to 36 hours
- Food
- Largely unaffected
- Dosing
- On-demand or 2.5–5 mg daily
- Max dose
- 20 mg on-demand
- Side effects
- Headache, flushing, back/muscle ache
Picking between them
- Choose sildenafil if you prefer to dose for a specific occasion, want the lowest-cost generic, and don't mind taking it on a lighter stomach. It's the classic on-demand pill.
- Choose tadalafil if you value spontaneity, dislike planning around a pill, eat dinner before sex, or want the daily low-dose option so you're 'always ready.' Daily tadalafil also treats urinary symptoms from an enlarged prostate — a two-for-one for many older men.
- The others: vardenafil behaves much like sildenafil but is sensitive to food; avanafil is the fastest (15–30 minutes) and most selective, with potentially fewer visual side effects, but is newer and often pricier.
Nuances worth knowing
- Give each drug a fair trial — guidelines suggest an adequate dose up to about 8 times before concluding it doesn't work for you.
- Don't stack them. Switching off tadalafil's long half-life to another PDE5i needs a gap (often 48–72 hours) — do this only with your clinician.
- After prostate surgery, a daily low dose of tadalafil is commonly used as part of penile rehabilitation, though early use may not fully restore spontaneous, unassisted erections.
- Beware non-FDA-approved 'compounded' or online versions and supplements — they aren't equivalent to FDA-approved generics and may be contaminated or mis-dosed.
- Common, usually mild side effects: headache, facial flushing, stuffy nose, indigestion. Rare but urgent: vision or hearing loss, or priapism — stop and seek care.
Key takeaways
- PDE5 inhibitors are first-line for most men and effective, but they need arousal to work.
- Never combine them with nitrates or poppers — that's the one absolute safety rule.
- Sildenafil suits on-demand dosing; tadalafil suits spontaneity and has an 'always ready' daily option.
- Give any pill a fair trial (about 8 attempts at an adequate dose) before judging it.
Not sure which option is right for you?
Dr. Mutter can review your health history, medications, and lifestyle to recommend the right first-line approach — and adjust the plan if it needs refining.