Cialis belongs to a drug class called phosphodiesterase type 5 inhibitors , or PDE5 inhibitors. BMJ Clinical research ed. Can low testosterone cause ED? People with heart conditions should never take ED medications without consulting a doctor. For example, alternative treatments or reduced dosage medication may be advisable while dangerous interactions between common heart medications ie, nitrates and PDE5s should be avoided. What blood pressure medication does not cause erectile dysfunction? What to expect from your doctor Your doctor is likely to ask you a number of questions. · The approved dosages of Cialis for ED, BPH symptoms, or both, are between mg and 20 mg a day or as needed. Dosages higher than 20 mg a day haven’t been studied, and it’s not known what. can start in about 10 minutes, can take 1 hour for maximum effect. typical starting dose is 50 mg, can be increased to mg. Tadalafil (Cialis) when you need it, or regularly every day. can. How to Make ED Drugs Work Better. Watch what you eat when you take your pill. Make sure you take the right drug for you. Give it enough time to work. Check with your doctor to see if you need to.