Some pills marketed as herbal remedies for erectile dysfunction contain drugs that should be available only by prescription, researchers report.
Sildenafil (Viagra) and tadalafil (Cialis), known as phosphodiesterase inhibitors, improve erections in some men by increasing blood flow to the penis during arousal. But the prescription compounds can cause fatal complications if used at the same time as certain drugs that have effects on the heart and blood vessels.
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