• ​Facial flushing where the skin on your face feels hot
• Headache
• Nausea
• Back pain, muscle aches, pain in arms and legs
• Nasal congestion

Priapism (an erection that will not go away) - If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis.

Sudden vision loss in one or both eyes - Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION).

Sudden hearing decrease or hearing loss - Some people may also have ringing in their ears (tinnitus) or dizziness.

The symptoms of a drug allergy include one or more of the following:

• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

Inform your healthcare professional if:

• You are allergic to this medication or any of the other ingredients of this medication
• You are taking medicines called Nitrates (such as sublingual nitroglycerin (also known as Glycerin Trinitrate or GTN), Isosorbide Mononitrate or Isosorbide Dinitrate), as the combination may lead to a dangerous fall in your blood pressure. Nitrates must be withheld at least 24 hours after the last dose of Sildenafil or Vardenafil, and 48 hours after the last dose of Tadalafil.

Tell your doctor if you are taking any of these medicines which are often given for relief of angina (chest pain).  If you are not certain, ask your healthcare professional.

• You are taking medicines called Alpha-1 Blockers (such as Tamsulosin, Terazosin, Prazosin, Alfuzosin), as the combination may further lower your blood pressure. In order to reduce the chances of these symptoms occurring, you should be on a regular daily dose of your Alpha-blocker before you start drugs for erectile dysfunction.
• You recently had a stroke or a heart attack, low blood pressure or uncontrolled high blood pressure
• You have severe heart, liver or kidney problem
• You have certain rare inherited eye diseases (such as retinitis pigmentosa)
• You have a stomach ulcer or bleeding problem
• You have a deformity of your penis

Female patients of childbearing age (using this medication for the treatment of pulmonary hypertension) should take precautions to avoid pregnancy by seeking advice from gynecologist for effective contraceptive methods. If you suspect you may be pregnant, inform your cardiologist as soon as possible.

​Avoid taking grapefruit,or grapefruit juice as they may interact with your medication and increase the risk of side-effects.

Inform your healthcare professional if you are taking or intend to take any other medication, supplements, traditional medications or herbal remedies.

This includes certain medications such as:

• Antibiotics
• Anti-fungal medications
• Medications used to treat human immunodeficiency virus (HIV) infection
• Medications for epilepsy (fits)

• ​Do not stop taking your medication without checking with your healthcare professional as it may worsen your condition
• This medication may be taken with or without food.
• This medication is usually started at a lower dose. Medication dosage will be adjusted based on your condition and your response to this medication will be monitored closely.

• ​Take the missed dose as soon as you remember. If it is close to the time for your next dose, skip the missed dose and go back to your normal time. Do not take 2 doses at the same time or extra doses.
• Do not take more than the dose prescribed to you.

​Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.