Tadalista 40 mg (tadalafil) should generally not be taken together with other ED drugs such as: Sildenafil (Viagra and generics) Vardenafil (Levitra/Vilitra and generics) Avanafil (Stendra and generics) Combination ED products containing PDE-5 inhibitors (for example, tadalafil + another ED medicine) Taking two PDE-5 inhibitors together does not usually improve erections, but it can increase the risk of side effects, especially: Very low blood pressure Dizziness or fainting Severe headache Fast heartbeat Vision or Tadalista 40 mg problems (rare) Prolonged erection lasting more than 4 hours (priapism, an emergency) A 40 mg tadalafil dose is higher than the commonly prescribed as-needed ED dose (usually up to 20 mg), so combining it with another ED medicine is particularly risky unless specifically directed by a specialist. If one ED medicine is not working well, doctors usually adjust the dose, timing, address underlying causes (such as diabetes, blood pressure, stress, or low testosterone), or consider other treatments rather than combining ED pills.