A massage is like passive exercise... think back to the feeling after exercising for the first time or coming back to exercise after a long period of inactivity. You were probably pretty sore the next day - it probably lasted a couple of days. The same is true for massage. Massage causes the same reaction because it increases the activity of the Lymphatic system, which cleanses the blood of impurities. Most therapists will tell you to drink plenty of water; a fully hydrated body goes through the cellular detoxification more easily. In order to stay hydrated most experts agree that you should drink ½ of your body weight in ounces every day (even more during the summer or during heavy exercise when you are sweating profusely).
Another issue to consider is trying to not take on much activity for 12 hours after the massage (other than gentle exercise). This gives your body time to absorb the changes that occur in your posture and physiology after a massage. We don’t think anything of resting after exercise. Massage is no different. This includes sufficient amounts of sleep to aid in recovery, especially after a deeper massage.
It is well documented by science that the mind and emotions effect the health of our bodies. The reverse is true, as well. Our body can effect our emotions, so don’t be too surprised if you feel a little cranky or irritable after a deep massage. It doesn’t mean you need to go to a counselor necessarily, although we would never discourage that. It can just be a random effect of the body on the mind or emotions. Most of the time it will pass. However, if it doesn’t you should seek the help of a trained Doctor of Psychology or Psychiatry to discuss how those emotions may be chronically affecting your health without you even being aware of it.
Another thing to consider is the need to regularly perform stretches to maintain what your therapist has attained during the session. Stretching can be done safely every day, and most people find that they get the best results by being very consistent.
All of these things taken together will help you derive much more benefit from your valuable time and money spent on massage!