Filitra 40 mg side effects, the main steps are to use the lowest effective dose, avoid alcohol and grapefruit/grapefruit juice, and take it exactly as prescribed. Filitra 40 mg can cause headache, flushing, dizziness, stomach upset, and vision changes, and alcohol or grapefruit can make these more likely or worse. Practical ways to lower side effects: Take it only when needed, not more often than prescribed. Filitra 40 mg heavy alcohol use before or after taking it. Avoid grapefruit and grapefruit juice. Do not combine it with nitrates or other medicines your doctor warned about. If it is your first time using vardenafil, start only with medical advice, since 40 mg is a relatively strong dose. If side effects are mild, they often settle as the medicine wears off. If you get chest pain, fainting, severe vision changes, or an erection lasting more than 4 hours, seek urgent medical help.