VIVUS (Nasdaq: VVUS) shocked the market with seemingly unbelievable first quarter results, sending shares over 10% higher. They have since steadily declined. The lesson as always: if something seems to good to be true, it probably is. 

Sales of its obesity drug Qsymia doubled, but to the still low total of $9 million. More concerning prescriptions declined, despite the aggressive discount program for the drug.

In this episode of Market Check-Up, the Motley Fool's health-care focused investing show, analysts David Williamson and Michael Douglass discuss the quarterly results, obesity drug competition, and ultimately why Vivus investors should be concerned.