The most important part of a detox is waste elimination; removing toxins from your body.
For this to happen, people will first usually experience what is called a 'healing crisis'. This usually happens on the first 2-3 days of the detox and symptoms normally disappear by the 4th day.
Basically, the healing crisis is when the toxins are being released from the tissues and cells and have entered your blood stream. As the toxins are in your blood stream on their way to elimination people experience symptoms such as headaches, dizziness, feeling lethargic, etc.
The more toxins you have stored in your body, generally the more severe the symptoms will be. This is a normal part of detoxing and is actually a good sign that it is working. It may be uncomfortable for 1 day or 2, but it is a small price to pay for your long term health!