A recent study that compared the long-term effectiveness and safety of long-pulsed Nd:YAG and alexandrite lasers, individually and in combination, in long-term leg hair reduction showed that combination therapy did not have any additional benefit and caused more adverse effects.
Twenty individuals were treated in various spots with a Nd:YAG laser, an alexandrite laser, or a combination of those. They found that the most effective, least painful treatment was the alexandrite laser. It had an 84.3% reduction in hair versus a 73.6% reduction of the combined laser. The combination treatment also caused more burning (an unfortunate side effect of this procedure).
[Source: Archives of Dermatology]