Cialis (tadalafil) is prescribed for two main conditions: erectile dysfunction (ED) and the urinary symptoms caused by an enlarged prostate, a condition called benign prostatic hyperplasia (BPH). It can also be prescribed when both conditions occur together, which is common since they tend to affect men in the same age range. First approved by the FDA in 2003 for erectile dysfunction, it received an additional approval in 2011 for BPH symptoms.
Erectile Dysfunction
Erectile dysfunction is the most well-known reason Cialis is prescribed. The medication works by relaxing smooth muscle tissue in blood vessel walls, which increases blood flow to the penis during sexual arousal. It does this by blocking an enzyme that normally breaks down a chemical messenger responsible for keeping those muscles relaxed. The result is that erections are easier to achieve and maintain.
In phase 3 clinical trials, 81% of men taking the standard dose reported improved erections, compared to 35% of men taking a placebo. That’s a significant gap, and it’s one reason Cialis became one of the most widely prescribed ED medications worldwide.
What sets Cialis apart from similar medications is how long it lasts. Its effects can persist for up to 36 hours after a single dose, earning it the nickname “the weekend pill.” Some patients in clinical trials saw improvement as early as 30 minutes after taking it, though results vary. This extended window means less pressure to time the medication precisely around sexual activity.
Enlarged Prostate Symptoms
Cialis is also prescribed to relieve the lower urinary tract symptoms that come with an enlarged prostate. These include difficulty starting urination, a weak or interrupted urine stream, and the frustrating need to wake up multiple times during the night to use the bathroom. For many men, these symptoms significantly affect sleep quality and daily comfort.
The medication helps by relaxing smooth muscle tissue in the prostate, bladder, and the blood vessels that supply them. This improves blood flow and oxygenation to those tissues, which reduces the muscle tension that contributes to urinary obstruction. Research has also shown that this relaxation likely calms overactive nerve signaling in the pelvic area, which plays a role in the urgency and frequency many men experience. Over time, consistent treatment can make symptoms less severe and may reduce the likelihood that prostate surgery will be needed.
Because ED and BPH frequently overlap in men over 50, a single daily dose of Cialis can address both problems at once. This dual benefit is a practical advantage, since it means one medication instead of two.
How It’s Taken
Cialis is available in two dosing approaches. For erectile dysfunction alone, it can be taken on an as-needed basis before sexual activity. The alternative is a lower daily dose, taken at the same time each day regardless of when sexual activity might happen. The daily approach is the standard method when the prescription is for BPH symptoms, or for men dealing with both BPH and ED.
The daily option appeals to many men because it removes the need to plan around a pill. Since the medication is always active in your system, erections and urinary improvements happen more naturally throughout the day and night.
Important Drug Interactions
Cialis has one critical safety restriction: it cannot be taken with nitrate medications. Nitrates are commonly prescribed for chest pain and heart conditions, and they include drugs like nitroglycerin and isosorbide mononitrate. Both Cialis and nitrates increase levels of the same chemical messenger that relaxes blood vessels. Taken together, the combined effect can cause a dangerous drop in blood pressure.
This interaction is serious enough that the American College of Cardiology and American Heart Association recommend waiting at least 48 hours after taking Cialis before using any nitrate, and even then only with medical supervision. That 48-hour window is longer than for other ED medications because Cialis stays active in the body longer. Recreational “poppers” (amyl nitrate or nitrite) carry the same risk and should not be combined with Cialis under any circumstances.
Common Side Effects
Most side effects from Cialis are mild and tend to decrease with continued use. Headache is the most frequently reported, followed by indigestion, back pain, muscle aches, flushing, and nasal congestion. Back pain and muscle aches are somewhat unique to Cialis compared to other medications in its class, and they typically appear 12 to 24 hours after taking a dose and resolve within a couple of days.
The extended duration that makes Cialis convenient also means that side effects, when they occur, can last longer than with shorter-acting alternatives. For most men, these effects are manageable and don’t lead to stopping the medication.