Here is some interesting information in an article I read. I thought I'd share with everybody

Injection Problems

Sticking a needle into your body is not without risk'particularly if the person giving the injection hasn't been trained in the procedure. The common side effects of poor injection technique are as follows:

'Pain
'Bruising
'Scar-tissue buildup
'Nerve injury
'Infection or abscess
'HIV or hepatitis (from needle sharing)

Injection problems are unrelated to the type of drug inside the syringe. They are purely the result of the needle stick. It doesn't matter whether the syringe contains a steroid, growth hormone, insulin or synthol.

Pain. Intramuscular injection inflicts two forms of pain. The first is that sharp pinch as the needle penetrates the skin. The second is a deeper discomfort, as the injection pushes the muscle fibers apart, creating a pocket of fluid. The larger the volume of fluid, the greater the pain. Bigger muscles like the gluteals, or buttocks, and thighs can comfortably accommodate two to three milliliters of fluid. With smaller muscles like the shoulders one milliliter is about the limit. The fluid disappears as the drug gets absorbed, but the site remains slightly damaged and inflamed from the needle stick for a while longer. The degree of pain and how long the drug sits there depend on the type and brand of drug. For example, many steroid users report that injecting the drug Sustenon is like getting kicked in the butt by a horse. This long-acting, oil-based steroid sits in the muscle for several days, and the pain in the butt can last up to a week. If you inject into the same site within the space of a few days, you can double the amount of fluid, double the damage and double the pain. Water-based injectables like Winstrol are usually quicker-acting'they're more quickly absorbed and usually inflict less pain than the oil-based drugs.

Needle size also influences the amount of pain. Larger-diameter needles cause more damage than narrower ones. Needle diameter (in millimeters) is called the gauge. The larger the gauge, the finer the needle in thickness. Obviously, finer needles cause less tissue damage. The narrower the needle, however, the more difficult it is to push the fluid through, and the viscosity of oil-based steroids is simply too thick to pass through tiny needles. It's like a large pit bull trying to squeeze through a tiny cat door. And the small particles in some steroid suspensions, like Winstrol, can lodge in the barrel of small-diameter needles. As a rule of thumb, oil-based steroids can be injected with a 22-gauge (0.7 mm) needle, and the less viscous, water-based steroids can be delivered through 23- or 25-gauge needles. To improve comfort and safety with regular injections, it's better to use the smallest needle possible.

The length of the needle is also important. You need a 1 1/2-inch needle to deliver a deep intramuscular injection into larger muscles like the buttocks, whereas a shorter 5/8-inch or half-inch needle can be used to inject smaller muscles. If you sink a two-inch needle into a smaller muscle, you're likely to hit an underlying nerve or blood vessel.

Bruising. Every time a needle pierces muscle, a small amount of bleeding inevitably occurs. Under normal circumstances that's not a problem. But if the needle hits a blood vessel, the blood loss into the surrounding tissue can cause an unsightly (and painful) bruise, or hematoma. An injection-site bruise doesn't usually require treatment, but it will take a week or so to resolve. Bruising can be minimized by applying direct pressure on the injection site with a cotton swab or facial tissue. Keep pressing for a minute or two until you're sure the bleeding has stopped. Remember that a trained health-care worker draws back on the syringe before injecting. A back-flow of blood into the syringe indicates that the needle is in a blood vessel. Injecting an oil-based steroid directly into the bloodstream is hazardous, so the needle should be re-sited into muscle tissue before pushing the plunger.

Scar tissue. An injection needle actually damages muscle. As it plunges inside, it inflicts a tiny hole that heals by forming a scar. A small slither of scar tissue from one injection is no big deal; however, repeated needle sticks eventually create a large area of scarring. And subsequent injections into the hard scarification become more difficult and painful. It's like trying to stick a needle through the sole of a leather shoe'you'll need a hammer to get that needle in your butt. What many bodybuilders don't realize is that scar tissue is not normal muscle tissue'it doesn't contract. It just sits there in the muscle like a golf ball.

Site injection with the oil implant synthol'a practice I call 'spot welding'also creates scar tissue. The muscle tissue becomes inflamed, eventually forming a bump of scar tissue that resembles a tumor. The spot weld doesn't contract: It's false, a fake bulge, the kind you see on a padded bra.

So how can you minimize scar tissue buildup? You've got to reduce the number of injections in the same area. Give your poor butt a rest. There are several ways to achieve this: Stop injecting (duh!), cut back on injectable drugs, or rotate injection sites. Employing an injection-site rotation means using a different site each time you inject, thereby avoiding injecting into the same area for at least a week or two. To illustrate that point, let's say that you require regular intramuscular injections for a legitimate medical reason. The qualified technician would select a different injection site each time. For example: injection 1: right buttock; injection 2: left buttock; injection 3: right thigh; injection 4: left thigh; injection 5: right buttock again; and so on. Get the idea?

Nerve damage. Be warned that injecting into other muscle sites is not as risk free as it may seem. Over the years I've treated a number of bodybuilders with injection-related complications. It's scary how bodybuilders play their own version of Russian roulette with steroid injections, blindly stabbing different bodyparts without knowing the location of nerves and blood vessels. Most muscles are intimately adjacent to nerves, blood vessels and other important anatomical structures. For instance, the radial nerve lies immediately under the triceps horseshoe, the sciatic nerve under the lower portion of your glutes and the quadriceps teardrop directly over the lining of the knee joint. If your misplaced needle hits an artery or vein, the extra blood loss creates a good-sized bruise. Strike a nerve with your needle, and it feels like an electric shock. The damaged nerve can result in loss of feeling and muscle weakness.

So what are the safe injection sites? Unfortunately, an in-depth anatomy lesson is beyond the scope of this article, but medical texts will tell you that the three commonly used safe sites for administering intramuscular injections are as follows:

'the upper outer quadrant of the gluteal (buttocks) muscle
'the outer aspect of the mid-to-upper thigh
'the outer portion of the deltoid (shoulder) muscle.

Infection. Another possible side effect of poor injection technique is infection. That usually results from accidental contamination of a needle. All injections should be given using a sterile technique in a clean environment, without contaminating the end of the needle. The locker room of your local gym doesn't qualify as a sterile area.

Cleansing the skin with an alcohol swab can help reduce the risk of infection. If the needle does get dirty after it's removed from the sterile packaging, then there's a risk of introducing a bacterial infection under your skin. That can develop into an abscess filled with pus, which usually needs to be lanced or surgically removed. Fake or counterfeit steroids that have not undergone proper sterilization can also increase the risk of bacterial infection.

How can you tell when an injection site is infected? Well, the area is painful, swollen, red and warm to the touch. As the days pass, an infection gradually gets worse rather than better. In contrast, the pain and redness from a noninfected injection-site irritation resolves within a few days. If you don't get treatment for an infected injection site, the infection can spread, causing you to feel generally unwell, with a fever. If you reach that stage, you need to see a doctor right away.

Hepatitis and HIV. A more serious complication arises from sharing needles. That hazardous practice risks the transmission of HIV (AIDS) and hepatitis B or C. During the 1980s there were a few reported cases of HIV infection in bodybuilders sharing needles, but let's hope no one is crazy enough to share these toys nowadays.