How long do I need to wait to take Cialis from taking Viagra?

Interactions between your drugs
Major
sildenafil tadalafil
Applies to: Viagra (sildenafil), Cialis (tadalafil)

Using sildenafil together with tadalafil may cause blood pressure to fall excessively. The risk of other side effects such as dizziness, lightheadedness, fainting, headache, flushing, heart palpitations, and priapism (prolonged and painful erection unrelated to sexual activity) may also increase. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.

https://www.drugs.com/interactions-check.php?drug_list=2144-1395,2061-1352