Vidalista 20 mg (contains tadalafil) can cause headaches, and this is actually one of its more common side effects. The active ingredient, Tadalafil, works by relaxing and widening blood vessels (vasodilation) to improve blood flow. That same blood vessel widening can also happen in the brain, which may trigger a headache or pressure-like sensation. Other related side effects that sometimes occur with it include: Facial flushing (warmth or redness) Nasal congestion Dizziness Indigestion Mild back or muscle pain Headaches are more likely if: You take a higher dose (like 20 mg) You drink alcohol around the same time You’re dehydrated You’re sensitive to vasodilating medicines Most headaches are mild to moderate and temporary, usually improving as the medication wears off. But if the headache is severe, persistent, or comes with vision changes, chest pain, or fainting, that’s not normal and should be checked urgently.