Sildenafil vs. Tadalafil: main differences, dosages, side effects, and more
Remote Pharmacy Research Team
May 28, 2025
Sildenafil (Viagra) and tadalafil (Cialis) are two of the most prescribed medications for erectile dysfunction (ED). Both belong to the same class of drugs — PDE5 inhibitors — and work by improving blood flow during sexual stimulation. While they share a similar mechanism, they differ in timing, duration, dosing, and side effect profiles.
Understanding how these medications compare can help you choose the option that best fits your lifestyle, health needs, and treatment goals. In this guide, you'll find clear information about how they work, how long they last, how to take them safely, and what to expect in terms of results and side effects.
Erectile dysfunction (ED) is the inability to achieve or maintain an erection firm enough for sexual activity. It can happen occasionally, but when it becomes frequent or persistent, it may affect a man's confidence, relationships, and overall quality of life.
ED can result from various factors, including blood flow problems, nerve damage, hormonal imbalances, or psychological stress. It may also be linked to chronic conditions such as diabetes, high blood pressure, or cardiovascular disease.
Although ED becomes more common with age, it is not considered a normal part of aging. With proper medical evaluation and treatment, most men can improve or fully restore sexual function using medications like sildenafil or tadalafil.
Sildenafil is a prescription medication used to treat erectile dysfunction. It is part of the PDE5 inhibitor class and works by increasing blood flow to the penis during sexual stimulation. Sildenafil is best known under the brand name Viagra, though it is also widely available as a generic.
The medication is taken as needed, usually 30 to 60 minutes before sexual activity, and its effects last around 4 to 6 hours. It helps men achieve and maintain an erection but only works with sexual stimulation.
Sildenafil is typically recommended for men who want a shorter treatment window and prefer not to take a daily medication. It is not intended for continuous use and should not be taken more than once a day.
Tadalafil is also a PDE5 inhibitor, prescribed for erectile dysfunction and, in some cases, benign prostatic hyperplasia (BPH). It improves blood flow to the penis, allowing for a stronger and longer-lasting erection during sexual arousal. The brand name most associated with tadalafil is Cialis, though it is also available in generic form.
Tadalafil is known for its long duration of action — up to 36 hours, which allows for more flexibility and less pressure to time the medication closely with sexual activity. It can be taken as needed or once daily, depending on the treatment plan.
Because of its extended effect, tadalafil is often preferred by men who want more spontaneous intimacy or who engage in sexual activity more frequently.
Both Viagra (sildenafil) and Cialis (tadalafil) belong to a class of medications called PDE5 inhibitors. They work by targeting the same biological pathway: the enzyme phosphodiesterase type 5 (PDE5), which regulates blood flow in the penis.
During sexual arousal, the body releases nitric oxide, which triggers the production of cyclic GMP (cGMP) — a molecule that relaxes smooth muscle in the blood vessels of the penis, allowing them to expand and let more blood in. This increased blood flow results in an erection.
PDE5 breaks down cGMP. By inhibiting this enzyme, both drugs preserve cGMP levels for longer, maintaining blood flow and supporting a sustained erection. However, sexual stimulation is still required for this process to begin — the medication alone does not cause an erection.
While their mechanism is the same, the difference lies in how quickly they start working and how long they stay active. Sildenafil has a shorter duration and faster peak effect, while tadalafil has a longer half-life, offering a wider window of action.
Both sildenafil and tadalafil are proven to treat erectile dysfunction effectively, but they offer different experiences in terms of duration, timing, side effects, and convenience. Understanding these differences helps identify which option is better suited to each patient’s routine and goals.
Sildenafil typically lasts for 4 to 6 hours, making it a short-acting option. It reaches peak concentration about 1 hour after intake and is best used within a limited window.
Tadalafil remains active for up to 36 hours, offering a longer period of responsiveness. It takes effect within 30 to 45 minutes, and its extended duration allows for more flexibility and reduced pressure to time sexual activity precisely.
Sildenafil is taken as needed, with typical doses of 25 mg, 50 mg, or 100 mg, depending on tolerance and response. It is not used daily and should not be taken more than once every 24 hours.
Tadalafil is available in two formats:
This flexibility makes tadalafil an appealing option for men with more frequent sexual activity or those who prefer routine dosing.
Both medications share similar side effects, including headache, flushing, nasal congestion, and indigestion. Sildenafil is more likely to cause visual disturbances, such as blue-tinged vision or sensitivity to light.
Tadalafil may cause back pain or muscle aches, especially at higher doses. Because of its longer half-life, some side effects may last longer, but are generally well tolerated when taken as prescribed.
Both drugs are available in generic form, which makes them more affordable and widely accessible. Sildenafil is typically less expensive per dose, especially for as-needed use.
Tadalafil may cost more, particularly for daily dosing, but the added convenience and longer duration can justify the difference for some patients. Access and pricing may vary based on country, insurance, and pharmacy.
Both Viagra and Cialis are effective options for treating erectile dysfunction, but the best choice depends on your lifestyle, medical history, and treatment goals. While they share the same mechanism of action, their differences in timing, duration, and flexibility make each medication better suited to specific situations.
When deciding between sildenafil and tadalafil, timing is often the first consideration. Sildenafil is ideal for men who prefer a shorter window of effect and more control over when they take the medication. It works quickly and is effective for a few hours.
Tadalafil may be better for men who want more spontaneity or who are sexually active multiple times per week. Its long duration allows for flexibility without needing to plan closely around the dose.
Other factors include how often you experience ED, how your body tolerates the medication, how long you prefer the effects to last, and whether you also experience urinary symptoms related to BPH.
Daily dosing with tadalafil may also appeal to those looking for a more consistent solution that fits into their daily routine.
Before starting either medication, it’s important to consult with a licensed healthcare provider. Your doctor will review your overall health, medications you’re taking, and any potential interactions or risks. This includes checking for heart conditions, liver or kidney issues, or use of nitrate-based drugs.
A proper evaluation ensures that you receive the safest and most effective option, with a dosage tailored to your specific needs. Remote Pharmacy simplifies this process by connecting you with licensed providers online, offering guidance and treatment from the comfort of home.
Choosing to treat erectile dysfunction is a personal decision, and with Remote Pharmacy, it’s also simple, secure, and discreet. You can begin your treatment from the comfort of your home, with support from licensed healthcare providers who evaluate your needs and recommend the right medication for you.
There’s no need for in-person appointments or long waits. If you’re ready to take control of your sexual health, Remote Pharmacy is here to help — safely, privately, and on your terms.
Start today and move forward with confidence.