All the side effects except the skin rash normally reduce sequentially with successive doses. One individual, who had many weeks of diarrhoea following the first hookworm dose, found his symptoms greatly reduced the second time around and, after the third dose, there was no liquid diarrhoea at all during the side effect period, just very soft stools with a 'cow pat' consistency. After the fourth dose, his stools were virtually as normal, but remained slightly softer than they had been prior to infection.
The skin rash at the inoculation site may also recur during the gastrointestinal side effect phase, perhaps because the worms shed cells and debris from their skin as they migrate through the host's skin, and, when the worms attach and put the same kind of material (their skin) into contact with the host's immune system in the intestines, the host's immune system releases antibodies to those types of cells or proteins wherever they occur, whether in the intestine or in the skin.
Strangely, the first few hookworm doses produce a successively more pronounced skin rash, with the fourth or fifth inoculation leaving some people with a very impressive 'love bite', perhaps even surrounded by a halo of apparently bruised skin which can become raised and may be as itchy as the rash site itself. Apart from the skin rash, which tends to ease after a few days, all the other side effects typically come and go, and the experience can be very much like riding a roller-coaster. There is also enormous variation between individuals, with some people getting no symptoms at all, and others experiencing relentless fatigue, disabling abdominal pain and geysers of diarrhoea.
