Contraindicated Interactions

Sildenafil should not be used with the following medications due to the risk of dangerous interactions:

• Nitrate drugs (e.g. nitroglycerin, isosorbide dinitrate) – Can cause a severe drop in blood pressure.
• Guanylate cyclase (GC) stimulators (e.g. riociguat) – Can also intensify the blood pressure-lowering effects.

Potential Interactions

Sildenafil may interact with a wide range of other medications, including:

• Other erectile dysfunction drugs (e.g. tadalafil, vardenafil) – Can cause low blood pressure and other serious side effects.
• Certain antifungals, antibiotics, and antidepressants – Can increase sildenafil levels and side effects.
• Blood pressure medications, anticoagulants, and antiseizure drugs – May have interactions that require dosage adjustments.

Alcohol Interaction

While there is no direct interaction between sildenafil and alcohol, consuming alcohol while taking sildenafil may exacerbate certain side effects like flushing, nausea, and dizziness. Excessive alcohol intake can also impact the effectiveness of sildenafil for treating erectile dysfunction.

Supplement Interactions

The herbal supplement St. John’s wort may reduce the effectiveness of sildenafil. Other supplements generally do not have known interactions, but it’s still important to inform your healthcare provider about any supplements you are taking.

Key Precautions

1. Contraindicated with Nitrates and GC Stimulators:
   • Sildenafil should not be used with nitrate drugs (e.g. nitroglycerin) or guanylate cyclase (GC) stimulators (e.g. riociguat) due to the risk of severe and potentially life-threatening drop in blood pressure.
2. Interactions with Other Medications:
   • Sildenafil may interact with a wide range of other medications, including other ED drugs, certain antifungals, antibiotics, antidepressants, blood pressure medications, anticoagulants, and antiseizure drugs. Dosage adjustments may be required.
   • Concomitant use with potent CYP3A4 inhibitors (e.g. ketoconazole, erythromycin, cimetidine) may require starting with a lower 25mg dose of sildenafil.
3. Alcohol Consumption:
   • Consuming alcohol while taking sildenafil may exacerbate certain side effects like flushing, nausea, and dizziness. Excessive alcohol intake can also impact the effectiveness of sildenafil.
4. Patients with Bleeding Disorders or Peptic Ulcers:
   • There is no safety information on the administration of sildenafil to patients with bleeding disorders or active peptic ulceration. Sildenafil should be used with caution in these patients.
5. Lactose Intolerance:
   • The film coating of Viagra tablets contains lactose. Sildenafil should not be administered to men with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption.

Viagra (sildenafil citrate) works in the body by enhancing the natural process of penile erection through its mechanism of action. Here are the key steps:

1. Nitric Oxide Release: During sexual stimulation, nitric oxide (NO) is released in the corpus cavernosum of the penis.
2. Guanylate Cyclase Activation: NO activates the enzyme guanylate cyclase, which increases the levels of cyclic guanosine monophosphate (cGMP).
3. Smooth Muscle Relaxation: Increased cGMP levels lead to smooth muscle relaxation in the corpus cavernosum, allowing increased blood flow into the penis.
4. Erection: This relaxation and increased blood flow result in an erection sufficient for sexual activity.

Most Common Dietary Restrictions

The most common dietary restrictions include:

1. Vegetarianism and Veganism: Vegetarians avoid meat, poultry, and fish, while vegans avoid all animal products including dairy and eggs.
2. Lactose Intolerance: Inability to digest lactose, the sugar found in milk and dairy products.
3. Gluten Intolerance: Includes celiac disease and non-celiac gluten sensitivity, requiring avoidance of wheat, barley, and rye.
4. Religious Dietary Restrictions:
   • Kosher (Jewish): Strict rules around permitted foods, preparation, and mixing of meat and dairy.
   • Halal (Islamic): Specific requirements for animal slaughter and prohibited foods like pork.
   • Lent (Catholic): Abstaining from meat on Fridays during the Lenten season.
   • Mormon: Avoiding alcohol, coffee, tea, and caffeinated beverages.

Other Common Restrictions

5. Food Allergies: Reactions to specific foods like peanuts, tree nuts, shellfish, etc.
6. Keto Diet: Very low-carb, high-fat diet.
7. Raw Food Diet: Eating only uncooked, unprocessed plant-based foods.