Acne is not generally noted as a common side effect of laser hair removal.
More Info: Though laser hair removal has been proven inherently safe in numerous studies it is not without its minor side effects.  Redness and swelling are common side effects following treatment but are generally mild and disappear within a few days. More serious noted side effects have been blistering, bacterial infection, and skin pigmentation. 
How Laser Hair Removal Works
Lasers are used in this procedure to target the melanin in the hair follicle subsequently damaging the follicle to inhibit future growth. The hairs must be present in the follicle as a target for the laser so waxing, plucking, and electrolysis are to be avoided far in advance of the date the procedure is to be performed. The area should be shaved prior to the procedure because the laser needs to target the hair in the follicle shaft, not above the skin’s surface. Long hair above the skin’s surface that becomes heated through the laser may cause the skin to burn.
Best Candidates for Optimal Results
The best candidates for laser hair removal have dark hair and light skin. The laser is most effective on these candidates because there is little competing melanin in the skin for the laser to target.
Laser Hair Removal Not for These Candidates
Dark skinned people have the least effective results and experience the highest incidence of side effects due to the competing melanin surrounding the hair shaft. The treatment is also ineffective on blonde, white, or gray hair.
 “Complications of nonphysician-supervised laser hair removal.” National Center for Biotechnology Information. N.p., n.d. Web. 25 Apr. 2011. <http://www.ncbi.nlm.nih.gov/pmc/ articles/PMC2628842/
 ” Laser hair removal | http://www.aad.org.” American Academy of Dermatology. N.p., n.d. Web. 25 Apr. 2011. <http://www.aad.org/media-resources/stats-and-facts/cosmetic-treatments/laser-hair-removal>.