Tadalafil Tadalafil belongs to a group of medicines called Phosphodiesterase- 5 inhibitors. These open up the blood vessels, notably in the lungs to increase blood flow. With increased blood flow, more oxygen can be taken around the body to your muscles and organs. How to take it Tadalafil is taken as a dose of 20mg-40mg once a day. It doesn’t matter what time you take it. Tadalafil is available as 20mg tablets. Do not take tadalafil if you: • Are taking medicines called nitrates for chest pain (for example GTN spray). • Have a serious heart or liver problem. • Have recently suffered a stroke or heart attack. • Have low blood pressure. • Have a rare inherited eye condition, such as retinitis pigmentosa. Side effects Side effects with tadalafil causing people to stop treatment are quite rare. However the most common side effects are headache, back/muscle pains, flushing, nasal congestion, nosebleeds, indigestion, low blood pressure, sudden hearing loss and changes to your vision (especially the way you see different colours). Talk to your PH centre immediately if you notice any change in your hearing or vision. Other useful information Tadalafil is only available on prescription. The dosage prescribed for men with impotence is different to your dose for PH. Simply taking tadalafil will not cause men with PH to have erections, as you need to be aroused for it to work in that way. If you forget to take a dose of tadalafil, take it as soon as you remember but never take a double dose to make up for the missed one.