Vidalista 40mg contains tadalafil, a medication used to treat erectile dysfunction by increasing blood flow to the penis. It works by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which helps relax blood vessels. Nitrates, commonly prescribed for chest pain or angina, also work by dilating blood vessels. When taken together, both medications can cause a significant and dangerous drop in blood pressure, leading to symptoms like dizziness, fainting, or even heart attack. This combined effect is particularly hazardous, which is why Vidalista 40 is contraindicated for people using nitrates. This interaction can lead to severe cardiovascular complications.