Cialis (tadalafil) is a long-acting PDE5 inhibitor, the same drug class as Viagra, but with a 36-hour window instead of 4-6 hours. It's prescribed for erectile dysfunction, benign prostatic hyperplasia (the prostate-related urinary issues that come with age), and pulmonary arterial hypertension. Outside the prescription pad, a low daily dose has become one of the most widely used baseline tools in men's health.

The reason most men take 2.5-5 mg daily: improved endothelial function (how well your blood vessels dilate, one of the first things to decline with age), better systemic blood flow, lower pulse wave velocity and arterial stiffness over time, easier urination and fewer nighttime bathroom trips, healthier prostate tissue perfusion, stronger and more reliable erections without timing a pill, better morning wood (which keeps erectile tissue oxygenated), and a smoother side effect profile than the same total dose taken on-demand.

For women, the picture is less established but more interesting than the marketing suggests, more on that in the deep-dive.

Deep-dive

Dosage:

• Daily low dose, 2.5-5 mg once a day, taken at the same time each day. This is the workhorse protocol for ED, BPH, and the cardiovascular/endothelial benefits people are chasing. Most men land at 5 mg. 2.5 mg is the floor and is genuinely subtherapeutic for many; if you're paying for it, just go to 5 mg unless you're particularly sensitive
• On-demand, 10-20 mg, taken roughly 1-2 hours before sex, effects last up to 36 hours. Use this if you don't want drug in your system constantly or if 5 mg daily isn't strong enough for sex. Don't dose more than once every 24 hours
• Combining the two: if 5 mg daily isn't enough for a specific encounter, layering an additional dose is generally discouraged because of cumulative side effects. Some clinicians instead switch the patient to on-demand sildenafil for sex and keep tadalafil daily for the BPH/endothelial effects, this stacking is being studied formally
• For women, the only doses with trial support are 5 mg daily for 8-12 weeks. There's no on-demand female protocol with meaningful evidence. Expect a gradual response over weeks, not minutes
• Take with or without food. Unlike sildenafil, tadalafil's absorption isn't significantly affected by food or moderate alcohol. A heavy meal won't blunt it
• Avoid stacking with other PDE5 inhibitors (sildenafil, vardenafil, avanafil), nitrates of any kind including amyl nitrite "poppers," or riociguat. The interaction with nitrates is genuinely dangerous and can cause severe hypotension. This is the one hard rule
• Reduce dose if you have moderate liver or kidney impairment or are on strong CYP3A4 inhibitors (ketoconazole, ritonavir, itraconazole). Cap at 2.5-5 mg in those cases
• Forms: brand-name Cialis, generic tadalafil tablets (the cheap option since the patent expired in 2018), and compounded "troches" (lozenges) from telehealth pharmacies. Generic tablets are the standard, well-controlled, and a fraction of the cost

Here's what you can expect:

On 5 mg daily, most men notice within 1-2 weeks that morning erections come back, erections are firmer and more reliable, and urinary stream improves if BPH was an issue. The effect is steady rather than dramatic. There's no "feeling" the drug in the way you'd feel caffeine or modafinil, the only signal it's working is that things just work better.

On-demand 10-20 mg gives you a wide window, you can take it Friday night and still have an effect Sunday morning. This is the main reason it's preferred over sildenafil by most users and most partners, the partners' preference study found 79% of women preferred their partner being on tadalafil over sildenafil, primarily because the timing wasn't a constraint.

For women, expect a slow response, weeks not hours, and expect it to help with arousal and lubrication rather than desire. If nothing has changed at 8 weeks of 5 mg daily, it's probably not the right tool for your situation.

Side effects, when they occur, usually show up in the first week and either resolve or become tolerable.