The reason why people may have assumed it can cause an abcess is b/c when you have a water based substance and an oil based substance in a pin, the oil is going to come out much faster. Your going to try to use a harder push to get the oil out which is gonna cause the water based aas to squirt out way too fast. If they are perfecty blended it will work great but its hard to get. Also you can mix HCG with any aas in a syringe. HCG should be shot IM or SQ. Its kinda like b12,...it doesnt really make a big difference if its IM or SQ.