Some people are more sensitive and experienced Herx at higher amplitude. More is not necessary merrier and I believe, 5V has been chosen as optimal value. Increased killing rate has to be matched by sufficient detox and resupplying vital elements, such as minerals and vitamins as well as replenishing beneficial flora in GI tract. It all depends on what we're trying to eradicate and the location.
Dead remains can be more toxic than pathogen and they can be a hosts for other "species". Once the host is dead, the entire cell content spills into the environment - our body and can cause secondary problems.
For more details, please check the link from: