"Man Up Now" sounds like a pretty strong name for an "all natural" and "herbal" male enhancement product. But the FDA slammed those claims, warning consumers to "stop using them immediately."
The issue, says the agency, is the product uses "sulfoaildenafil, a chemical similar to sildenafil, the active ingredient in Viagra."
Like Viagra, sulfoaildenafil can have dangerous interactions with other prescription drugs such as nitrates, and can cause dangerously low blood pressure. But because consumers think they are taking a "natural" product they are usually not under a doctor's care.
Also, sulfoaildenafil has not undergone the same clinical trials as sildenafil, so all its effects are not known.