• Sildenafil: Approved for the treatment of erectile dysfunction (ED) and pulmonary arterial hypertension (PAH) under the brand names Viagra and Revatio¹.
• Tadalafil: Approved for the treatment of ED, benign prostatic hyperplasia (BPH), and PAH under the brand names Cialis and Adcirca².
• Apomorphine: Used off-label for the treatment of ED, primarily in Europe and other regions³.

• Sildenafil and Tadalafil: Both are phosphodiesterase type 5 (PDE5) inhibitors. They work by increasing nitric oxide levels, which enhances blood flow to the penis during sexual arousal, resulting in a firmer erection¹².
• Apomorphine: Unlike PDE5 inhibitors, apomorphine works on brain chemistry. It stimulates the hypothalamus to produce more dopamine, a neurotransmitter that regulates sexual desire and sensation³

• Sildenafil: Take approximately 30 minutes to 1 hour before sexual activity. It can be taken with or without food. Do not take more than once in a 24-hour period¹.
• Tadalafil: Can be taken daily or as needed. For as-needed use, take at least 30 minutes before sexual activity. For daily use, take at the same time each day, with or without food².
• Apomorphine: Typically taken sublingually (under the tongue) about 20 minutes before sexual activity. Follow your healthcare provider’s instructions³.

• Sildenafil and Tadalafil:
  • Headache
  • Flushing
  • Indigestion
  • Nasal Congestion
  • Dizziness
  • Visual Disturbances (blurred vision, changes in color vision)¹²
• Apomorphine:
  • Nausea
  • Dizziness
  • Fainting
  • Sweating³

• Sudden Vision Loss: Rare cases of sudden vision loss in one or both eyes¹².
• Sudden Hearing Loss: Sudden decrease or loss of hearing¹².
• Priapism: An erection lasting more than 4 hours requires immediate medical attention to prevent long-term damage¹².
• Severe Allergic Reactions: Symptoms may include rash, itching/swelling, severe dizziness, or trouble breathing¹²

• Nitrate Medications: Do not use if you are taking nitric oxide donors, including organic nitrates or nitrites, as it can cause a dangerous drop in blood pressure¹².
• Allergies: Avoid if you have a known allergy to any of the components¹².
• Guanylate Cyclase (GC) Stimulators: Do not use if you are taking medications like riociguat¹².

• Nitrates, Alpha-Blockers, and Antihypertensives: These can cause a sudden drop in blood pressure when taken with sildenafil or tadalafil¹².
• CYP3A4 Inhibitors: Medications like ritonavir, ketoconazole, itraconazole, and erythromycin can increase sildenafil and tadalafil levels in the bloodstream, leading to potential side effects¹².

• Medical History: Always inform your healthcare provider about all medications you are taking, including over-the-counter drugs, vitamins, and supplements. This helps to avoid potential drug interactions and side effects¹².

For more detailed safety information, please refer to the full prescribing information available on the FDA website:

• Sildenafil (Viagra) Prescribing Information
• Tadalafil (Cialis) Prescribing Information
• Sildenafil and Tadalafil Information

If you have any specific questions or concerns, always consult with your healthcare provider for personalized advice.