Tadalafil (Cialis) Side Effects: Common and Serious Risks
Tadalafil shares its core class of medication with sildenafil, and much of its safety profile is similar, but a few side effects appear more or less often, and its longer duration changes how some risks play out. This page summarizes what has been reported, key drug interactions, and who should avoid tadalafil.
Common Side Effects
- Headache
- Back pain and muscle aches
- Facial flushing
- Nasal congestion
- Indigestion
- Flu-like symptoms (less commonly reported)
Back pain and muscle aches are reported somewhat more often with tadalafil than with sildenafil, and typically appear 12 to 24 hours after a dose, resolving on their own. Because of tadalafil's long duration, mild side effects can also simply last longer than they would with a shorter-acting medication.
Key point: Back pain and muscle aches are the side effects most distinctly associated with tadalafil compared with sildenafil, though most cases are mild and temporary.
Serious Side Effects
As with sildenafil, rare but serious effects include sudden vision loss in one or both eyes (associated with NAION), sudden hearing loss, and priapism (an erection lasting longer than four hours). Any of these requires immediate medical attention.
Important: Sudden vision loss, sudden hearing loss, or an erection lasting longer than four hours are medical emergencies. Seek immediate care if any of these occur.
The Nitrate Interaction
Tadalafil carries the same nitrate warning as sildenafil: combining it with any form of nitrate medication, including short-acting versions used only occasionally for chest pain, can cause a severe and dangerous drop in blood pressure. Because tadalafil remains active in the body for up to 36 hours, this interaction risk lasts considerably longer after a dose than it does with shorter-acting medications, which is an important distinction for anyone who might need a nitrate medication urgently after taking tadalafil.
Alpha-Blockers and Blood Pressure Medications
Alpha-blockers, used for high blood pressure or an enlarged prostate, can have an additive blood-pressure-lowering effect when combined with tadalafil. Prescribers often manage this by starting at a lower tadalafil dose, adjusting timing between the two medications, or choosing a specific alpha-blocker known to have a smaller interaction risk.
Who Should Avoid Tadalafil
- Anyone taking nitrate medications in any form
- Anyone with a recent heart attack, recent stroke, or unstable angina
- Anyone with uncontrolled low blood pressure
- Anyone with certain inherited eye conditions, without specific prescriber guidance
- Anyone with severe kidney or liver impairment, without dose adjustment guidance
Daily Dosing and Side Effect Considerations
Because daily low-dose tadalafil keeps a steady level of the drug in the body, some patients report that mild side effects like headache or congestion are more noticeable in the first one to two weeks of daily use and then settle down. Anyone who finds side effects persistent or bothersome on a daily regimen can discuss switching to as-needed dosing with their prescriber. See our tadalafil dosage page for more on how the two dosing patterns compare, or our sildenafil side effects page for a direct comparison of the two drugs' safety profiles.