I began taking creatine after having a small cyst removed from my abdomen. I could only perform minor exercises, and I thought this might sustain a fair amount of muscle tone for a month or two while I recovered. After a month of taking it, I (and my girlfriend - whose patience I deeply appreciate) noticed an increase in mood swings and irritability, as well as being quite antsy. After a second month went by, I stopped taking creatine as my workouts were back on track.

Six months later, I sustained a minor rotator cuff injury, and started on creatine again to enhance the recovery process as I exercised using the large 'rubber bands' given me by my physical therapist. I believe that it did, in fact, increase my recovery time and I noticed that irritability and mood swings began to return. This is when I began to think it might be creatine related; however, I wasn't fully convinced since both times I had injuries which made it somewhat difficult to sleep.

Having investigated several Web sites to find if my moodiness was a common side effect of creatine, I found virtually nothing to that effect. I then decided to investigate for myself. I began taking creatine again three months later. After two weeks, I was near full-blown temper tantrums, which would come from nowhere, and last for only minutes. I stopped taking it at that time, and have since calmed to my normal self. After telling a friend about this, he explained that his brother had identical side effects, which stopped a week or two after quitting creatine.

Bear in mind that I was taking about 3/4 of the recommended dosage while drinking the proper amounts of water. I am FIRMLY convinced that creatine causes detrimental cognitive effects in some. Be aware of this.