Viagra is not recommended while taking medication for hyperthyroidism, Viagra generic name is sildenafil citrate. Hyperthyroidism is a disorder of hypermetabolism and sympathetic nervous excitation caused by overproduction of thyroid hormones. Sildenafil citrate is a medication used to treat erectile dysfunction in men by dilating the cavernous body of the penis to help it become erect. Hyperthyroidism is usually characterized by a rapid heartbeat, increased metabolism, and a fear of heat and sweating, and after taking sildenafil citrate, men can aggravate the symptoms of hyperthyroidism itself. Rapid heartbeat and over-excitement cause oversized load to the heart, which may induce sudden death in severe cases. To sum up, taking sildenafil citrate during medication for hyperthyroid patients may lead to thyroid crisis, so this behavior is prohibited, and if you feel unwell, consult a doctor in time.