Any time you take any steroid, it is going to slow or eventually stop your natural production of test. The longer your cycle and or the higher your doses, the harder that shut down can be. You want to run a PCT with ANY cycle you do. Then, if the cycle was 8 wks long, take another 6-8 wks to recover and let your body get back to normal. Orals will throw your body out of wack much worse than most injectables. They have to pass through the liver to enter the blood stream and are designed to make it through without being destroyed. This process damages the liver. Thankfully, the liver will regenerate itself, to a point. Over time, repeatedly doing oral steroids can cause some serious consequences to your health. I have also found that orals tend to hit my HDL much harder than injects. The best way to use an oral, is as an additonal steroid, in a longer injectable cycle. So if you were to run a test cycle of 500mg EW for 10 to 12 wks, which is what I reccomend to new users, you can add in an oral for the first 4-6 wks to "kick start" your cycle, while you wait for the longer acting test to build up. This way, you can use a smaller dose of your oral and keep the duration of use down. IMO, many of the harmful things you hear about steroids on health, are related to the use of orals. 

For the future, I would suggest running a moderate dose of test as the base of your cycle and if you want to use an oral, keep it limited. Don't get me wrong. I am not against orals at all. It's just important to find moderation and look at long term health. The longer you use gear, the higher the doses will go. If you are only using orals, the doses required to continue getting results are going to become increasingly unhealthy for your body. Most of the time, I will not use orals in a cycle, I use the at the end of contest prep most often, but when I'm trying to gain muscle, I will try to play it safer. Here is how I would outline a good cycle for a first time injectable cycle. 

1-12

test e or cyp 350-500mg EW

adex 2-3x wk at .5mg

1-6

dbol at 20-30mg ED

You can make some killer gains on a cycle like this. 2 Wks after your last shot of test, you will want to start PCT. A good, basic PCT would be nolvadex at 40mg ED for a wk, followed by 2 more wks of 20mg. For any cycle you do, make sure to run your PCT, bud! You work hard in the gym and the kitchen to make your gains, so do everything you can to regain your natural production of test, so that you can maintain the muscle you have developed on cycle