Aggressive Energy
A.E. is present if a erythema appears on the skin around the needle that is different to your dummy needles or if there is a big change in the C.S.O.E. or pulses of a person.

If there is a reddening that seems to be A.E. after about 10 minutes, leave the needles in until the A.E. drains.  If not, you may remove the needles and proceed with your treatment.
Aggressive energy can be described as energy that has become contaminated or polluted it can also be thought of as evil (Xie) qi as opposed to healthy or upright (Zheng) qi.

If present, it is best to drain this qi before starting to treat the person at their constitutional level and before you start to transfer energy across the Ko and Sheng Cycles.
A.E. may come from both internal sources such as emotional upsets or external such as damp, cold and dryness.  If a persons Zheng/ Healthy qi or Wei/ Protective qi is strong usually this qi is transformed and dissipated. 

Sometimes over time this A.E. mounts up inside the body, stagnates and become toxic.

It is hard to diagnose if a person has a problem with A.E. but it sometimes can be seen as chaos in the person or on the pulses. The best course of action is to test for A.E. on the first treatment or if you feel there is something in the way of a patient progressing. A.E. is only found on the Yin Organs.
The Way to Test and Clear Aggressive Energy

Have you patient sitting up in a comfortable position, maybe leaning against the table

Mark the Yin Back Shu points (Lung, Pericardium, Liver, Spleen, and Kidney (not Heart)

Insert needles into these points, bilaterally in a very shallow way, no more than .1 of a cun deep.

Insert a dummy needle about 2 centimeters away from 2 or 3 of the Back Shu points, to test if any reaction noted is only skin sensitivity.
A.E. will move from the originating organ along the Ko  cycle.  If someone has A.E. in 4 organs this can be fatal.  If you find a lot of A.E. on the Kidney or Pericardium you may test for A.E. in the Heart, as the polluted Qi may have made it across to the Heart.  If you find a lot of A.E. consider repeating the treatment the next visit, as more may of surfaced.