Everyone has a different opinion of what is best and for different reasons it seems. My personal experience was I started out on oral estrogen but after a lot of research it started to make me nervous.
The high doses of estrogen that must be taken orally does increase the chances of clotting and is very hard on your liver. A liver function test should be done before your endo prescribes any estrogen. Even a healthy liver, which can normally handle the extra load, can eventually suffer damage after long term exposure. I thought maybe the transdermal patch might be an option but recent discoveries have shown that many of these patches are releasing huge amounts of estrogen much quicker than they were designed to which means the clotting issue raises it's ugly head again. Since oral estrogen was out and the patch was proving to be just as, or even more, dangerous I chose to go to injections.
The theory behind the safety of them is because the estrogen is injected deeply into the large muscle groups it is absorbed into the system at a much slower, therefore safer, rate and less estrogen is needed overall. My endo has fully supported this decision and my reasons for them so I'll continue my intramuscular injections until some other research study comes out and says this method is unsafe also LOL. I have always hated needles despite the fact I spent years working EMS. There is something inherently wrong about sticking something like that into your own body but considering the options I gladly stick myself every other week.
Any estrogen is going to increase your chance of clotting. Learn the pro's and con's of ingestion, absorbtion and injection. Try to avoid the behaviors that may increase the chance of clotting such as smoking. Make sure your endo is very experienced in not just HRT but in HRT as it pertains to transgendered individuals, there is a difference. Don't take your endo's word as gold...research the informantion that he or she gives you and make your own decision or even consult another endo for thier opinion. An extra doctor visit is a small price to pay for your life.
I just realized I got off topic a little there. Obviously it depends on how much estrogen you are injecting as to how much is being released but your endo should be monitoring your estrogen levels during this process to make sure you are at a "safe" level. I noticed a difference in breast tenderness when I switched from oral to injections but it was short lived. The breast growth issues isn't so much based on the method of estrogen of administration but of levels and genetics. My breast size has easily passed my roommates size by double in the same amount of time on the same dosages and administration method. Her mother was small breasted and my mother was large breasted.
