Abnormally high or low blood pressure. Eye disease such as non-arterial arterial ischemic optic neuropathy (NAION), which causes loss of vision or if you have retinitis pigmentosa. Allergic to sildenafil or any other ingredient. 100mg tablets.cimetidine in Kamgra for the treatment of ulcers, antibiotics such as erythromycin and rifampicin, verapamil or diltiazem (for high blood pressure), ritonavir or saquinavir (for HIV), itaconazole (for HIV); Like amlodipine for high blood pressure.