There are different types of retinoids and different products with each type of retinoid as an active ingredient. Retinyl palmitate, retinol, retinaldehyde, adapalene, tretinoin, isotretinoin, and tazarotene are all various forms of retinoids, which in turn are various forms of Vitamin A. The difference between each type of retinoids is explained in detail further below. But first, here is a chart of retinoid products, categorized by the type of retinoid used in the product, to hopefully clarify some things for you: As you can see from the above chart (which by no means is a complete representation of all the retinoid products out there), there are a lot of retinoids on the market. Retinoids are available in various brands (different companies, brand names, generics), types (retinol, tretinoin), concentrations (0.25%, 0.1%), and formulations (gel, cream). Most retinoids are natural retinoids, but some are synthetic. Some retinoids are available at the drug store, while others you can only get at the doctor's office.
All of these factors influence the strength and effectiveness of each type of retinoid. Keep reading for further clarification. Retinyl palmitate, retinol, and retinaldehyde are available over-the-counter. The rest of the retinoids are only available through prescriptions, though some online pharmacies (Canadian, Indian, or otherwise) offer various generic versions without one. You usually need a doctor's prescription to legally order a generic of a brand name prescription product, but different online pharmacies operate under different policies, especially if they are in other countries. Tazarotene is the strongest retinoid, while retinol is the weakest (retinyl palmitate is even weaker than retinol - more on that below*). The strength of a retinoid depends on the type of retinoid. Your skin is only able to use a retinoid when it's in retinoic acid form. Therefore, all types of retinoids are converted to this state by your skin before it can even be used. How does this have anything to do with a retinoid's strength?
Allow me to explain. When you apply a retinoid product that is retinoic acid (ex. Retin-A), your skin is able to use it immediately because it's already in the proper form. However, if you use a product with retinol, the retinol first has to be converted into retinaldehyde and then the retinaldehyde has to be converted to retinoic acid before your skin can use it. Therefore, retinol is weaker than retinaldehyde and retinaldehyde is weaker than retinoic acid. Retinol is the weakest of those three because it takes your skin two extra steps for it to be converted to retinoic acid before it can be utilized. For each conversion step, there is also some uncertainty as to how much of the retinoid was actually converted in the oxidation process (i.e. the retinol may not be 100% converted into retinoic acid). Therefore, the fewer the conversions it takes to get to retinoic acid, the stronger the retinoid. Retinyl palmitate and retinol are the more common (and cheaper) retinoids available.
Retinyl palmitate is weaker than retinol, but many skin care products are labeled as "retinol" treatments, even if there is only retinyl palmitate as an active ingredient and no actual retinol ingredient. This, unfortunately, causes a lot of unnecessary confusion because retinyl palmitate is not the same thing as retinol. Retinyl palmitate must first be converted to retinol, which is then converted to retinaldehyde, which is finally converted to retinoic acid, with some loss during each conversion step. Retinol takes two metabolic steps to be converted into retinoic acid, while retinyl palmitate takes three steps. Therefore retinyl palmitate is weaker than retinol, which is weaker than retinaldehyde, which is weaker than retinoic acid. The extra conversion step it takes for retinyl palmitate to be converted into usable retinoic acid means that you have to use a product with a very high concentration of retinyl palmitate to make it effective. Most products with retinyl palmitate (also labeled "vitamin A" products) tend to be moisturizing, but they are often too weak to provide any major skin benefits, especially in terms of anti-aging.
At the very least, you are better off using a retinol product (check the ingredient list for it on the product label). Aside from the type of retinoid, each individual product also has its own individual retinoid concentrations. For example, Retin-A comes in 0.025%, 0.05%, and 0.1% formulations. The 0.025% would be the weakest version of Retin-A, while the 0.1% would be the strongest. The formulation of the retinoid also has a factor in its strength, but you can read more about the difference between gel and cream vehicles here. It might also be helpful to familiarize yourself with how natural and synthetic retinoids are different. Deciding on which type of retinoid and which percentage strength is best for you will depend on how your skin tolerates the retinoid. Generally, you go with the strongest retinoid you can tolerate with the least amount of irritation, even if that retinoid is considered weak. If your skin can't handle tazarotene, there's no reason to subject it to Tazorac.
The irritation from the product would far outweigh its benefits. Most dermatologists initially prescribe Differin for acne because it is the gentlest one out of all the prescription retinoids. However, if Differin isn't strong enough for you, you could try moving up to Retin-A. If you feel Retin-A isn't doing a good job, you could then give Tazorac a try. It takes trial-and-error to figure out which retinoid is best for you. Things can get pretty confusing because there are so many different types of retinoids, strengths, percentages, and product formulations. Some retinoids are also used for acne treatments, while others target anti-aging. Dermatologists always have lots of samples, so make sure you test some retinoids out for a few weeks before purchasing the real thing. Having lots of patience and using retinoids the right way is the key to finding the best type of retinoid for your skin. Gel vs. Cream Formulations for RetinoidsAuthor information1Department of Physiological Chemistry, University of Lund, Sweden.AbstractThe aim of the present study was to characterize the intestinal absorption of retinol and retinyl palmitate in thoracic duct and bile duct fistulated rats and to investigate the effect of a simultaneously administered lipase inhibitor, tetrahydrolipstatin (THL).
Absorption was determined as lymphatic recovery over a 24-hr period, including an initial 12-hr continuous intraduodenal infusion of either [11,12-3H]retinol or [11,12-3H]retinyl palmitate given in emulsified glyceryl trioleate or in mixed micellar solution of monoolein and oleic acid. From micellar dispersion, labeled retinol and retinyl palmitate were recovered in the lymph to 50-60% and both to the same extent. Administered in emulsified form, labeled retinol from fed retinyl palmitate was recovered to 47%, but retinol from fed retinol to only 18%. THL (10(-4) M) in the infusate had no significant effect on the recovery of 14C-labeled oleic acid. The recovery of label from emulsified glyceryl tri[1-14C]oleate was significantly decreased at this concentration of THL (76.5% vs 19.6% recovery). When administered in emulsified form, retinol absorption was not significantly affected by THL at 10(-4) M, while retinyl palmitate absorption was very significantly decreased (5.0% compared to 47.8%).