What is Ernafil?

Ernafil is a brand medication that contains Sildenafil, which belongs to a class of medications called phosphodiesterase inhibitors. It works by increasing blood flow to the penis during sexual stimulation, to cause an erection. It is therefore used to treat erectile dysfunction (impotence) in men.

How to use it?

Ernafil is available as tablets. It can be taken with or without food.

For erectile dysfunction,
Take 50mg approximately 1 hour before sexual intercourse, may adjust depending on response in the range of 50-200mg. Maximum dosage is 200mg once daily.

What are the side effects of Ernafil?

Common side effects of Ernafil include flushing, headachedizziness, nasal congestion, and stomach discomfort.

Who should not take Ernafil?

  • People allergic to Ernafil or any component of the formulation
  • Patients who are currently taking nitrates regularly or as emergency medication
  • Patients who recently had myocardial infarction or stroke

Pharmacist Tips:

  • This medication can make you dizzy. Avoid driving or operating machinery until you know how you respond to Ernafil.
  • Report to your doctor immediately if you experience sudden visual or hearing loss.
  • Seek medical assistance in case of prolonged erection (over 4 hours) after using Ernafil.
  • People who have existing cardiovascular conditions must avoid using Ernafil and any other phosphodiesterase inhibitors.
  • Do not use more than once daily as it can cause severe side effects.

Common dosing schedule: 
Take Ernafil no more than once daily. Use at approximately one hour prior to sexual intercourse with at least 24 hours between doses.

This schedule is for reference only, adjustments may be made according to individual needs.


Some common medications Ernafil may interact with:

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Ernafil in Hong Kong?

In Hong Kong, Ernafil is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.


For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Ernafil in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.

Available dosage
  • 25mg / 50mg / 100mg (Tablets)
Drug class
Sub class
Phosphodiesterase Inhibitors
Generic Names
Other drugs in same class
Used for: Prevention of thromboembolic events
Chinese name:
Used for: Erectile dysfunction, Pulmonary arterial hypertension, Benign Prostatic Hyperplasia (BPH)
Chinese name:
Used for: Prevention of thromboembolic events
Chinese name: