I've been on Androgel for several years, and highly recommend it. One issue with me is that sometimes my body's natural production spikes up, and it is necessary to cut back on the supplement for a couple of days. This is much easier with Androgel.
The standard shots are not testosterone injected into the blood, as someone incorrectly claimed above. The liver quickly destroys testosterone, so it must be slowly infused into the body over an extended period. Your T-level is the balance achieved between the rate of gradual infusion, and the rate of metabolism by the liver.
Rather, the testosterone in standard injections is dissolved in an oil. A blob of this oil is injected into your muscle or fat, where it sits until it is slowly is absorbed over the period until you next shot (days to weeks). As it is absorbed, the testosterone is gradually released. Although cheap and simple, this scheme is bad for several reasons:
1. To function properly, the body needs to see a daily cycle of testosterone, which naturally spikes up in the morning (hence, morning wood!) and falls during the day. Since the injected oil infuses the T at a constant rate, you don't get the cycle.
2. If you are like me, and need to adjust the dose according to mood and libido, this is hard with a standard injection, because a supply lasting days to weeks (according to the method chosen by your doctor) is put in the body at once, and no reduction is possible if your level starts to get too high. (There is such a thing as too much T; typical symptoms in my experience include acting like an asshole.)
The Androgel also works on a gradual release principal, but on a day-to-day basis, not several days to weeks like standard shots. When you apply the gel to your skin, the testosterone is quickly absorbed into the skin and subcutaneous fat, which acts as a reservoir for the T, even after the gel is washed off. The testosterone stored in this reservoir passes gradually and continuously into the blood over a period of about a day. However, the nature of the process is that the T level spikes when the gel is first applied, then the rate of infusion slows down as the reservoir becomes exhausted. So, if you apply Androgel in the morning, you closely mimic the body's natural testosterone cycle.
In my case, I find I have to adjust the dose downward for a day or two now and then, presumably because my body decided to naturally produce some. (We've never been able to figure out why my body is erratic, but the test results show that it is.) With Androgel, this is easy: just skip a daily dose.
There are a number of gels similar to Androgel, such as Testim, Axiron, Vogelxo, etc. They are all similar, except that the application instructions differ a bit. All of these are expensive, because you pay for convenience, and they are also wasteful. Only about 10% of the testosterone in the gel actually ever makes it into the blood stream. The rest washes off. (Injectables, however, eventually deliver 100%.) Eventually, the product will become a generic (although DEA controlled) drug, and prices will drop. The testosterone used is chemically synthesized from soybeans, and is not all that expensive. (By the way, soybeans contain stuff that mimics sex hormones, including female hormones. As such, there is some debate if men should ever eat soy products. However, soy is so prevalent in modern processed food, that it is almost impossible to avoid.)
There is an additional form of gel, really a cream, which is prepared by compounding pharmacies by mixing testosterone powder with a greasy cream. This is not as nice to use as the alcohol-gel-based products like Androgel, and the absorption mechanism is a bit different. On the other hand, if your insurance doesn't pay for the fancy Androgel, this can be a cheaper alternative. However, you'll have to find a doctor who understands how to work with a compounding pharmacy, and how not to get ripped off.
There are disadvantages of all the topical creams/gels. You can't get the application area wet or sweaty for hours after application, so if you have a morning gym routine, etc, this could be a problem. The gel can rub off onto others, such as your wife or children. There have been cases where very small children entered something like puberty years early (including extraordinary development of the penis) because of contact with their father, who was using topical testosterone. If these are considerations, a gel might not be a good idea.
Another issue with gels is the available body surface area. I am sufficiently hairy in the application areas listed in the Androgel instructions that I cannot actually apply the gel as instructed. However, with my doctor's guidance, I have found enough smooth skin in other areas to make it work. (Curiously, despite premature male pattern baldness and a very hairy upper body, I have low T. The only giveaway is that I never grew armpit hair until I started on Androgel a decade ago at age 43.)
There are also patches, which work like the smoking-cessation nicotine patches, but with testosterone. These usually stay on for a few days.These aren't very popular, but are the best solution for some people. Unlike an injection, if you find you need to drop the dose immediately, you can peel the patch off.
The sub-dermal implants work on pretty much the same schedule as the injected oil. If you can get away with a steady dose, this might work, but if you need variability in the dose, this is not a good option.
There are some new products in clinical trials that work by injecting a small amount of drug into subcutaneous fat, from where it is slowly absorbed, on a daily basis. They use a simple, painless injector like an epi-pen. This might overcome a lot of the disadvantages of other methods, but I don't think anything has made it to market yet. (Drug approval is a painfully slow process in the USA.)
