Certain helminth species have been reported in the medical literature to provoke anaphylactic reactions, but others provide protection against anaphylaxis.
- An enteric helminth infection protects against an allergic response to dietary antigen -- Full text | PDF
Although therapeutic helminths have been available for self-treatment since 2003, and the number of individuals using helminthic therapy was estimated in 2015 to be between 6,000 and 7,000  there have been no reports of the treatment causing a severe anaphylactic reaction. There have been three reports of large doses of hookworms causing moderate anaphylactic reactions, but none of these required emergency treatment.
There have been several reports from self-treaters confirming success in preventing anaphylaxis.
For more accounts of success with anaphylaxis, see the following page section.
A number of people have reported that, while hosing helminths, their reactions to insect stings have been greatly reduced. This effect may be of value to someone who is prone to developing anaphylaxis after being stung.
Anyone with anaphylaxis who decides to self-treat with helminths should continue to ALWAYS carry at least one epinephrine auto-injector, even if the treatment proves to be effective, because of the possibility of an unexpected reduction in protection due to something harming, or even killing, their worms.
In the case of the non-human worms, HDC and TSO, which need to be re-dosed frequently, there may be a reduction in the level of protection if a dose is forgotten or delayed. Several people who are using HDC have reported a return of disease symptoms due to issues with supply, or simply due to forgetting to take a dose on time.  Obviously, a failure to adequately maintain one's helminth colony will increase the chance of an anaphylactic reaction and the risk of fatality.
It is also possible for a reduction in protection from the human helminths, NA and TT, if the self-treater is exposed to something that kills or stresses their colony (see the Human helminth care manual) or if the colony is not actively maintained by the regular addition of supplementary doses. (See Hookworm dosing and response: Supplementary doses.)