* Tanning Pills
 
Tanning pills typically contain the pigment canthaxanthin.

Even though the FDA has approved the use of canthaxanthin as a color additive in food, it has not approved its use as a tanning agent.

The larger quantities of canthaxanthin than the amount used as a food coloring must be ingested to change skin color.
And after canthaxanthin is consumed, it is deposited throughout the body, including in the skin, which turns an orange-brown color, and also the internal organs (liver, brain, etc.).

- Canthaxanthin-based tanning pills have been linked to dangerous side effects, including hepatitis (inflammation of the liver) and canthaxanthin retinopathy (formation of yellow deposits in the retina of the eye).

* Tanning Accelerators

Most tanning accelerators are lotions or pills that contain the amino acid tyrosine. Manufacturers of these products believe that the tyrosine stimulates and increases melanin formation, thereby accelerating the natural tanning process. On the other hand, more scientific data is needed to determine the validity of these claims and to assess the safety of using large amounts of tyrosine. 
 
* Why Do Tans Fade?

Skin gets a lot of wear and tear, so it naturally regenerates itself.

- Every 35-45 days the outer layer of the skin, the epidermis, is completely replaced.
- Since skin pigment is found in this upper layer, any natural or added pigment will be sloughed away in about one month's time.
It is why natural tans fade and why many self-tanning products recommend you re-apply the product every few days to maintain your tan.