Depends on how heavy your parasite load, what kind of parasites you are cleansing and which formula you are using. I only weigh 100 pounds and I've been cleansing for over a year. I cannot tolerate the recommended dose of one formula that I use. I had to take 5-10 times more than the recommended dose of another formula I tried, in order for it to have any effect at all. It also depends on your constitution, your lifestyle and your diet. Some products work better for some people than others.
If you don't get the results you are looking for with one product, try something else. I recommend starting with the least expensive ones and going from there. Be sure to read the labels. If you feel really bad, start with half the recommended dose to be safe. If you can tolerate that, up the dose. I quite often increase to a dose that is higher than what is recommended on labels, especially if I was getting results at the recommended dose, and the results stopped.
But I am going for a really deep cleanse because my immune system was impaired by viruses, so I am at risk of the disease coming back really fast and hitting me hard. I want to be sure I get it all, and/or keep things in check, in case I am re-exposed. If you are young and your immune system is strong, and you get rid of a mother load, or two, then your body might be able take over and keep things in balance, without going over the recommended amount.
This is just my opinion, based on personal experience. It is not intended to take the place of professional medical advice. Take what you like and leave the rest and all that good stuff.