Constipation (tightness of the bowels; absence or rarity of movement, and smallness of amount discharged) is almost always present during the first days of a fever, of any kind except typhoid. Even in that, also, although early looseness of the bowels is more common, there is in a few cases a short time of constipation.

Pregnant women are very apt to have the bowels constipated, from the partial obstruction produced by the pressure of the enlarging uterus upon the lower bowel (rectum). Sea-sickness, also, is very often attended by slowness of the bowels. But the most obstinate and alarming constipation is that of obstruction of the bowels; as in strangulated rupture, or in intussusception.

Diarrhea (excessive liquid flow from the bowels) is symptomatic of various disordered conditions. It is present as a rule in typhoid fever, and is common in advanced pulmonary consumption. It is an essential part of the attack in cholera-morbus, epidemic cholera, and cholera infantum (summer complaint of infants). It occurs frequently by itself, particularly in warm climates, and in the summer season.

Discharges in diarrhoea are either natural (fecal), mucous (slimy), bilious, or watery. In cholera-morbus, which may be met with anywhere, the passages are nearly natural or bilious, unless near the end of a very bad case. Epidemic cholera is distinguishable partly by the rice-water-like abundant discharges, with no biliary color at all.

Dysentery is recognized by scanty but frequent bloody discharges, with griping pains, and a disposition to bear down. Slime (mucus) is apt to be mingled with blood, and at a later period in severe cases there may be pus.