In 2013, the American Academy of Clinical Toxicology and European Association of Poisons Centres and Clinical Toxicologists published a second update to their position statement on gastric lavage for GI decontamination (original 1997, 1st update 2004).
Here are the highlights :
Gastric lavage should not be performed routinely, if at all, for the treatment of poisoned patients.
Further, the evidence supporting gastric lavage as a beneficial treatment even in special situations is weak.
In the rare instances in which gastric lavage is indicated, it should only be performed by individuals with proper training and expertise.

Bottom line : 
Gastric lavage generally causes more harm than good. It should not be thought of as a viable GI decontamination method.
References :
Benson BE, et al. Position paper update: gastric lavage for gastrointestinal decontamination. Clin Toxicol 2013 Feb 18. [Epub ahead of print]

Source:"Chinese emergency medical magazine" editorial department