Vilitra 40 The upper limit of tolerable Vardenafil dose is known to be approximately 80 mg but one must ensure that they take only the prescribed dose. An overdose of this drug can cause mild to intense side effects, depending on the quantity of overdose. Some symptoms are- nausea, diarrhea, lower-back pain, myalgia, dizziness, etc. Therefore, you should not take a double dose or overdose on this medicine.