Medical Review by Jennie Stanford, MD, FAAFP, DipABOM
Summary:
- Cialis® and Viagra® are two effective treatments for erectile dysfunction (ED). Both have mechanisms of action that involve inhibiting PDE5 to increase blood flow to the penis.
- Cialis® is known for its prolonged effect, lasting up to 36 hours and earning it the nickname “the weekend pill,” while Viagra® is effective for about 4 to 6 hours, requiring more planning for sexual activity.
- Both medications share common side effects such as headaches, flushing, and nausea, but also have unique side effects. They have similar contraindications and drug interactions, including interactions with nitrates and certain other medications.
- Both Cialis® and Viagra® are available in generic forms, which can be more cost-effective. They are widely accessible in both physical pharmacies and online platforms.
Cialis® and Viagra® are two of the most popular treatments for erectile dysfunction—but which one is right for you?
Knowing how to choose between these two medications can make your plan for treating ED safer and more effective, so our team of US-based health practitioners is here to help with a point-by-point comparison of both options.
Understanding Cialis® (Tadalafil):
Cialis®, generically known as tadalafil, plays a crucial role in ED treatment. Its mechanism of action involves inhibiting the enzyme phosphodiesterase type 5 (PDE5). This inhibition leads to an increased level of cyclic guanosine monophosphate (cGMP), resulting in the relaxation of smooth muscles and increased blood flow to the penis, thereby facilitating erections.
The duration of Cialis®’s effect is notably prolonged, lasting up to 36 hours. This extended period is a defining feature of Cialis®, earning it the nickname “the weekend pill”. The recommended dosages of Cialis® vary, including 2.5mg, 5mg, 10mg, and 20mg. The specific dosage should be determined by a healthcare professional based on individual needs.
Learn if Cialis® is right for you
Learn if Tadalafil is right for you
Understanding Viagra® (Sildenafil):
Viagra®, known by its generic name sildenafil, is another primary medication used in ED treatment. It shares a similar mechanism of action with Cialis®, inhibiting PDE5 to increase cGMP levels in the penile tissue. This process facilitates the relaxation of muscles and promotes blood flow, aiding in achieving and maintaining erections.
The duration of Viagra®’s effect is shorter than that of Cialis®, typically lasting about 4 to 6 hours. Viagra® is available in doses of 25mg, 50mg, and 100mg, with the initial prescribed dose often being 50mg. The exact dosage should be tailored to the individual’s needs under medical guidance.
Learn if Viagra® is right for you
Learn if Sildenafil is right for you
Comparing Cialis® & Viagra®
Side effects
Both Cialis® and Viagra® have unique side effects, although they also share some common ones. We’ve listed these below—but first, here’s a Venn diagram to help you understand the similarities and differences at a glance:
Cialis® (tadalafil) side effects
- Headache
- Flushing
- Stuffy or runny nose
- Back pain
- Nausea
- Indigestion or heartburn
- Muscle aches
Serious side effects (rare): Priapism (prolonged erection), sudden changes in hearing or vision, vision changes like seeing a blue tinge.
Source: Ei Lilly & Company
Viagra® (sildenafil) side effects
- Headache
- Flushing
- Stuffy or runny nose
- Back pain
- Nausea
- Upset stomach or indigestion
- Abnormal vision (blurred vision, changes in color vision)
- Muscle pain
- Dizziness
- Rash
Serious side effects (rare): Priapism, sudden hearing loss or vision changes, outlying risk of heart attack symptoms (mostly in individuals with heart disease).
Source: Pfizer
Contraindications & interactions
Both medications have similar contraindications and drug interactions due to their similar mechanisms of action.
Common contraindications
- Use of nitrates, commonly prescribed for chest pain.
- Severe heart or liver problems.
- Recent stroke or heart attack.
- Low blood pressure or uncontrolled high blood pressure.
- Certain rare inherited eye diseases.
Drug interactions
- Blood pressure medications, particularly alpha-blockers.
- Other ED medications or PDE5 inhibitors.
- Certain antifungal medications and antibiotics.
- HIV protease inhibitors.
- Grapefruit juice can also affect the metabolism of both drugs.
Cost & availability
Both Cialis® and Viagra® are available in generic forms, which significantly reduces their cost. Insurance coverage for these medications varies—in some cases, they may not be covered at all.
Availability is widespread, with the option to purchase from both physical pharmacies and online platforms.
Duration of effect
Cialis® (tadalafil): Cialis® can remain effective for up to 36 hours. This extended period allows for more spontaneity and less need to time the medication with sexual activity.
Viagra® (sildenafil): Generally effective for 4 to 6 hours, Viagra® requires more planning with regard to timing sexual activity. It typically takes about 30 to 60 minutes to start working.
In review: Cialis® vs. Viagra® at a glance
| Cialis® (Tadalafil) | Viagra® (Sildenafil) | |
| Generic Name | Tadalafil | Sildenafil |
| Mechanism of Action | Inhibits PDE5, increasing cGMP levels, leading to relaxed muscles and increased blood flow | Same as Cialis® |
| Duration | Up to 36 hours (known as “the weekend pill”) | 4 to 6 hours |
| Dosages | 2.5mg, 5mg, 10mg, 20mg | 25mg, 50mg, 100mg (initial dose often 50mg) |
| Unique Side Effects | Vision changes like seeing a blue tinge | Upset stomach or indigestion, abnormal vision, dizziness, rash |
| Common Side Effects | Headache, flushing, stuffy/runny nose, back pain, nausea, muscle aches, priapism (rare) | Headache, flushing, stuffy/runny nose, back pain, nausea, muscle pain, priapism (rare) |
| Serious Side Effects | Priapism, sudden changes in hearing/vision (rare) | Priapism, sudden hearing loss or vision changes, heart attack symptoms (mostly in people with a history of heart disease) |
| Contraindications | Nitrates, severe heart/liver problems, recent stroke/heart attack, certain eye diseases | Same as Cialis® |
| Drug Interactions | Blood pressure meds, other ED meds, certain antifungals/antibiotics, HIV protease inhibitors, grapefruit juice | Same as Cialis® |
| Cost & Availability | Available in generic form; varies by insurance and pharmacy, widely available | Same as Cialis® |
| Recommended Use | Better for spontaneous sexual encounters due to long duration | Requires planning for sexual activity due to shorter duration |
Find appropriate ED medication with help from Lemonaid Health
While your personal preferences will play a role in helping you choose between Viagra® and Cialis®, it’s also vital to consult a qualified healthcare provider before using either option. We will be able to review your medical history—including any risk factors or other medications you are currently taking—in order to make an appropriate recommendation that puts your safety first.
Learn more about the ED medications available with Lemonaid Health, and find a treatment plan that works for you.Viagra® is a registered trademark of Pfizer Inc. Cialis® is a registered trademark of Lilly ICOS LLC.
