Sunless tanners are products commonly sporting the ingredients Diltydroxyacetone or DHA, a color additive that darkens the skin by reacting with amino acids on the skin’s surface.  A bronzer is more of a temporary, almost paint on product. 

Then you can also take tanning pills.  One example is canthalaxanthin uses can cause nausea, cramping, diarrhea, severe itching, and welts.  Use of these pills has also been linked to decreased vision.  These are not FDA approved and do not give a true tan.  The import of these products are not prohibited by the United States.  So obviously don’t recommend the tan pills.

Another option is what’s called a tanning accelerator.  These increase the body’s natural production of melanin with the chemicals psoralen (found in limes) and tyrosine, an amino acid.  While not approved for this use, they are safe, though you should still wear sunscreen.