Noopept is generally well-tolerated in humans with a large therapeutic window and is only rarely associated with adverse events.
However, there are a few side effects of Noopept that you should be aware of. One comparative study of Noopept and Piracetam in the treatment of organic brain diseases noted the following side effects associated with Noopept: increased sleep disturbances, irritability and increased blood pressure. However, as compared with Piracetam, the use of Noopept was associated with a 1.8-fold lower level of undesirable effects. The quoted study published the following table of possible Noopept side effects.
Anecdotally, some users have reported that Noopept may cause headache.