There are few known hazards for discrete trial training. However, it has been heavily criticised by some people on the autism spectrum. For example, the website autism.wikia.com (Open in New Window), accessed on 29 February 2016, contains a detailed list of criticisms of ABA and DTT in particular from people on the autism spectrum.
There are no known contraindications for this intervention. However Smith (2001) reported
".. several cautions about DTT are noteworthy: First, the method must be combined with other interventions to enable children to initiate the use of their skills and display these skills across settings. Second, early in treatment, children with autism may require many hours of DTT per week, although controversy exists over precisely how much is appropriate. Third, to implement DTT effectively, teachers must have specialized training. Despite these limitations, DTT is one of the most important instructional methods for children with autism."
Schreibman et al (2015) reported
".. research showed that highly structured interventions such as DTT, while effective in teaching skills, sometimes led to (1) child failure to generalize newly learned skills across multiple environments and circumstances, (2) the presence of escape /avoidance challenging behaviors, (3) lack of spontaneity and (4) overdependence on prompts."