From the Guidelines
Sildenafil is recommended to be prescribed at a starting dose of 50 mg taken approximately one hour before sexual activity, with a maximum frequency of once daily, as supported by the most recent and highest quality study 1. The dose can be adjusted between 25 mg and 100 mg based on effectiveness and tolerability. For older patients (over 65), those with liver or severe kidney impairment, or patients taking certain medications like protease inhibitors, a lower starting dose of 25 mg is recommended. Sildenafil should be taken on an empty stomach or after a light meal for optimal absorption, as high-fat meals can delay its effectiveness. The medication works by enhancing blood flow to the penis during sexual stimulation by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which regulates blood flow in the penis. It's essential to note that sildenafil only works with sexual stimulation and doesn't increase sexual desire. Common side effects include headache, flushing, indigestion, nasal congestion, and visual disturbances. Sildenafil should not be taken with nitrate medications as this combination can cause a dangerous drop in blood pressure, as indicated in various studies 1. However, the most recent guideline from 2018 1 provides the strongest evidence for the recommended dose and usage of sildenafil. Key points to consider when prescribing sildenafil include:
- Starting dose: 50 mg
- Maximum frequency: once daily
- Adjustment of dose: based on effectiveness and tolerability
- Special considerations: lower starting dose for older patients, those with liver or severe kidney impairment, or patients taking certain medications.
From the FDA Drug Label
DOSAGE & ADMINISTRATION The recommended dose of sildenafil tablets is 20 mg three times a day (TID). Administer sildenafil tablet doses 4-6 hours apart. In the clinical trial no greater efficacy was achieved with the use of higher doses. Treatment with doses higher than 20 mg TID is not recommended. The recommended dose of Sildenafil (Viagra) is 20 mg taken three times a day (TID), with doses administered 4-6 hours apart 2.
From the Research
Recommended Dose of Sildenafil
The recommended dose of Sildenafil (Viagra) is as follows:
- The usual starting dose is 50mg taken when needed, approximately 1 hour before sexual activity, with a maximum dose of 100mg once daily 3, 4, 5, 6.
- Lower doses, such as 25mg, may be used in elderly patients, those with hepatic or renal impairment, or patients receiving certain medications, such as cytochrome P450 enzyme CYP3A4 inhibitors 3.
- The dose may be adjusted based on efficacy and tolerance, with some studies using a flexible-dose approach 5, 6.
Special Considerations
- In patients with idiopathic Parkinson's disease, a fixed dose of 50mg approximately 1 hour before sexual activity, not more than once daily, has been shown to be effective 4.
- The combination of sildenafil with l-arginine has been studied, with some evidence suggesting improved efficacy compared to sildenafil alone 7.
- Sildenafil has been shown to be effective and well-tolerated in men with erectile dysfunction across various age groups, including those 75 years and older 6.