Tadalafil: what it does, how long it lasts, and quick facts

Tadalafil (brand name Cialis) is a medicine most people use for erectile dysfunction (ED) and for urinary symptoms from an enlarged prostate (BPH). One thing people notice fast: a single dose can help for up to 36 hours, so it’s nicknamed the "weekend pill." That doesn’t mean it works continuously for two days, but it gives a much longer window than other ED pills.

How to use tadalafil safely

There are two common ways to take tadalafil. For as-needed use, most start with 10 mg taken 30–60 minutes before sex. Doctors may lower it to 5 mg or raise it to 20 mg depending on effect and side effects. For daily use (helpful if you want more spontaneity or have BPH), the usual dose is 2.5–5 mg once a day at the same time. Don’t take more than one as-needed dose in 24 hours.

If you have kidney or liver problems, or are older, your doctor may suggest lower doses. Always follow a prescriber’s advice — self-adjusting doses can cause unwanted reactions.

Side effects, interactions, and red flags

Common side effects are mild: headache, flushing, stuffy nose, indigestion, back or muscle pain. Serious but rare problems need immediate care: an erection lasting over 4 hours (priapism), sudden vision loss, or chest pain. If any of these happen, get emergency help.

Never combine tadalafil with nitrates (nitroglycerin for chest pain) — the mix can cause a dangerous drop in blood pressure. Also avoid it with riociguat. Strong antibiotics or antifungals (like clarithromycin or ketoconazole) and some HIV meds can raise tadalafil levels; some seizure meds reduce them. Alcohol in large amounts can make side effects worse and lower blood pressure too.

Storage is simple: keep tablets at room temperature, dry and out of reach of kids. Check expiry dates and avoid pills that look different from what you were given before.

Want to buy tadalafil? It’s prescription-only in many countries. Use a licensed pharmacy — online or local — that requires a prescription, lists a physical address, and provides pharmacist contact. Be wary of sites with rock-bottom prices, no reviews, or that skip the prescription step. Generic tadalafil is common and cheaper; it’s fine when it comes from a reputable source.

If you’re unsure whether tadalafil is safe for you — for example, if you have heart disease, take nitrate meds, or have serious kidney/liver issues — talk to a doctor first. A short conversation now prevents big problems later.

Got more questions about dosing, side effects, or how to spot a legit online pharmacy? Reach out to a pharmacist or clinician — they can give guidance tailored to your health and other meds you take.