This section is from the book "The Hygienic System: Fasting And Sun Bathing", by Herbert M. Shelton. Also available from Amazon: The Hygienic System Vol III Fasting and Sun Bathing.
Under the head of danger signals or complications, works on fasting usually list uncontrollable vomiting, persistent hiccoughs, a persistent, very erratic pulse, extreme weakness, fear of starvation, or an unreasonable and persistent determination to break the fast. The last three of these, I think, may be properly considered as signs of possible danger.
Great Weakness: This is not always a danger signal; but may be in some cases. Although it usually causes the practitioner to terminate the fast, this is due more to fear on his part than to any actual danger to the patient. Persistent extreme weakness is more likely to prove a danger signal, although this is so rare that I have seen but one such case.
Erratic Pulse: This may sometimes be a danger signal, but is not so in most cases. The heart will bear careful watching in such cases, and the fast may be terminated if the practitioner deems this advisable. An erratic pulse is usually of short duration, and should be taken seriously only when it is lasting.
A very rapid pulse or a very low, feeble pulse is usually considered a danger sign. This is certainly not always so. I have frequently continued fasts with a very rapid pulse, and I have continued others when the pulse was so low that one could hardly count it. All such symptoms must be considered in relation to the general condition of the patient and not in isolation.
Difficult Breathing: Dr. Kritzer lists the following symptoms that should be carefully watched because "they are nature's warnings to discontinue the fasting:" "palpitation of the heart; dysnea (difficult breathing); vomiting, hiccoughs, night sweats, a rapid, thin, wiry pulse, extreme nausea," The experienced practitioner knows that these are not indications for breaking the fast, and that they are not danger signals. I have witnessed the development of difficult breathing during a fast in but few cases and I have not seen it mentioned in any of the literature on fasting. It must be an exceedingly rare occurrence and, if and when it does occur, must be considered in relation to the general condition of the patient.
Retention of Urine: This is a very rare occurrence. I have never seen it develop. Authors attribute it to insufficient water drinking; but this cannot be the cause. Hot sitz baths and hot enemas are advised to secure relaxation. I do not favor their use. A catheter may be employed if necessary. Dr. Christopher Gian-Cursio reports a few cases of suppression of urine. In one case he secured a flow of urine by resort to a vaginal douche. No catheter was used. He says he much prefers fasters to have other reactions as this creates a great amount of fear in the patient and their panic-stricken "friends." Carrington mentions one case in which there was "prolonged retention of urine toward the end of a prolonged fast."
Delirium: This condition is of very rare occurrence; but may develop in those who have taken large quantities of nerve paralyzing drugs, or who are very toxic. The delirium is of short duration, and by itself should cause no apprehension. Should it develop in connection with suppressed urine, extreme weakness, rapid, feeble pulse and other signs of prostration, it should be considered a sign of danger. Such dangers do not arise from the fast, but from other causes.
Petechiæ: These are small purplish hemorrhagic spots in the skin which are chiefly associated with severe fevers, such as typhus, and are supposed to be indicative of great prostration. I have seen them develop in about a dozen fasters during more than thirty years of conducting fasts. Only two of these fasting patients have been young; the remainder have been well past middle life. They appear in patients who are in very low states of nutrition. This development has not been observed in any of the longest fasts I have conducted, while three or four of them have been in comparatively short fasts. The patients have at no time been prostrated. They probably mean great weakness of the capillary walls so that these break easily, permitting the blood to flow into the skin. It has been my practice to break the fast immediately upon their appearance. Only in one instance was the fast carried several days beyond their appearance. In this patient no harm resulted from extending the fast.
There are really few danger signals that develop during a fast and these are extremely rare. Perhaps in all cases these are due to something other than the fast. Due to popular prejudices against fasting and to the violent opposition of the medical profession to the procedure, practitioners who employed fasting hesitated to continue a fast in the face of developments they considered danger signals. Should the patient die they are likely to be accused of starving him to death and sentenced for manslaughter.
Ten thousand patients may die after swallowing poisonous drugs or after having one or more of their organs removed and no one is held responsible; but let one patient die while fasting and an autopsy is at once ordered to fix responsibility for death. This hindered, for a long time, progress in knowledge of fasting and prevented the discovery that what were thought to be danger signals often were not.