The World Health Organization (WHO) recommends rehydrating a severely undernourished child who has diarrhea relatively slowly. The preferred method is with fluids by mouth using a drink called oral rehydration solution (ORS). The oral rehydration solution is both slightly sweet and slightly salty and the one recommended in those with severe undernutrition should have half the usual sodium and greater potassium. Fluids by nasogastric tube may be use in those who do not drink. Intravenous fluids are recommended only in those who have significant dehydration due to their potential complications. These complications include congestive heart failure. Over time, ORS developed into ORT, or oral rehydration therapy, which focused on increasing fluids by supplying salts, carbohydrates, and water. This switch from type of fluid to amount of fluid was crucial in order to prevent dehydration from diarrhea.

Breast feeding and eating should resume as soon as possible. Drinks such as soft drinks, fruit juices, or sweetened teas are not recommended as they contain too much sugar and may worsen diarrhea. Broad spectrum antibiotics are recommended in all severely undernourished children with diarrhea requiring admission to hospital.

To prevent dehydration readily available fluids, preferably with a modest amount of sugars and salt such as vegetable broth or salted rice water, may be used. The drinking of additional clean water is also recommended. Once dehydration develops oral rehydration solutions are preferred. As much of these drinks as the person wants can be given, unless there are signs of swelling. If vomiting occurs, fluids can be paused for 5–10 minutes and then restarting more slowly. Vomiting rarely prevents rehydration as fluid are still absorbed and the vomiting rarely last long. A severely malnourished child with what appears to be dehydration but who has not had diarrhea should be treated as if they have an infection.

For babies a dropper or syringe without the needle can be used to put small amounts of fluid into the mouth; for children under 2, a teaspoon every one to two minutes; and for older children and adults, frequent sips directly from a cup. After the first two hours, rehydration should be continued at the same or slower rate, determined by how much fluid the child wants and any ongoing diarrheal loses. After the first two hours of rehydration it is recommended that to alternate between rehydration and food.

In 2003, WHO and UNICEF recommended a reduced-osmolarity ORS which still treats dehydration but also reduced stool volume and vomiting. Reduced-osmolarity ORS is the current standard ORS with reasonably wide availability. For general use, one packet of ORS (glucose sugar, salt, potassium chloride, and trisodium citrate) is added to one liter of water; however, for malnourished children it is recommended that one packet of ORS be added to two liters of water along with an extra 50 grams of sucrose sugar and some stock potassium solution.

Malnourished children have an excess of body sodium. Recommendations for home remedies agree with one liter of water (34 oz.) and 6 teaspoons sugar and disagree regarding whether it is then one teaspoon of salt added or only 1/2, with perhaps most sources recommending 1/2 teaspoon of added salt to one liter water.

Treating malnutrition, mostly through fortifying foods with micronutrients (vitamins and minerals), improves lives at a lower cost and shorter time than other forms of aid, according to the World Bank. The Copenhagen Consensus, which look at a variety of development proposals, ranked micronutrient supplements as number one.

In those with diarrhea, once an initial four-hour rehydration period is completed, zinc supplementation is recommended. Daily zinc increases the chances of reducing the severity and duration of the diarrhea, and continuing with daily zinc for ten to fourteen days makes diarrhea less likely recur in the next two to three months.

In addition, malnourished children need both potassium and magnesium. This can be obtained by following the above recommendations for the dehydrated child to continue eating within two to three hours of starting rehydration, and including foods rich in potassium as above. Low blood potassium is worsened when base (as in Ringer's/Hartmann's) is given to treat acidosis without simultaneously providing potassium. As above, available home products such as salted and unsalted cereal water, salted and unsalted vegetable broth can be given early during the course of a child's diarrhea along with continued eating. Vitamin A, potassium, magnesium, and zinc should be added with other vitamins and minerals if available.

For a malnourished child with diarrhea from any cause, this should include foods rich in potassium such as bananas, green coconut water, and unsweetened fresh fruit juice.

Medical treatment can directly or indirectly cause weight loss, impairing treatment effectiveness and recovery that can lead to further weight loss in a vicious cycle.

Many patients will be in pain and have a loss of appetite after surgery. Part of the body's response to surgery is to direct energy to wound healing, which increases the body's overall energy requirements. Surgery affects nutritional status indirectly, particularly during the recovery period, as it can interfere with wound healing and other aspects of recovery. Surgery directly affects nutritional status if a procedure permanently alters the digestive system. Enteral nutrition (tube feeding) is often needed. However a policy of 'nil by mouth' for all gastrointestinal surgery has not been shown to benefit, with some suggestion it might hinder recovery.

Early post-operative nutrition is a part of Enhanced Recovery After Surgery protocols. These protocols also include carbohydrate loading in the 24 hours before surgery, but earlier nutritional interventions have not been shown to have a significant impact.

Some medications can cause weight loss, while others can cause weight gain.

The least intrusive weight loss methods, and those most often recommended, are adjustments to eating patterns and increased physical activity, generally in the form of exercise. The World Health Organization recommended that people combine a reduction of processed foods high in saturated fats, sugar and salt and caloric content of the diet with an increase in physical activity.

An increase in fiber intake is also recommended for regulating bowel movements. Other methods of weight loss include use of drugs and supplements that decrease appetite, block fat absorption, or reduce stomach volume. Bariatric surgery may be indicated in cases of severe obesity. Two common bariatric surgical procedures are gastric bypass and gastric banding. Both can be effective at limiting the intake of food energy by reducing the size of the stomach, but as with any surgical procedure both come with their own risks that should be considered in consultation with a physician. Dietary supplements, though widely used, are not considered a healthy option for weight loss. Many are available, but very few are effective in the long term.

Virtual gastric band uses hypnosis to make the brain think the stomach is smaller than it really is and hence lower the amount of food ingested. This brings as a consequence weight reduction. This method is complemented with psychological treatment for anxiety management and with hypnopedia. Research has been conducted into the use of hypnosis as a weight management alternative. In 1996 a study found that cognitive-behavioral therapy (CBT) was more effective for weight reduction if reinforced with hypnosis. Acceptance and Commitment Therapy ACT, a mindfulness approach to weight loss, has also in the last few years been demonstrating its usefulness.

In many cases of diarrhea, replacing lost fluid and salts is the only treatment needed. This is usually by mouth – oral rehydration therapy – or, in severe cases, intravenously. Diet restrictions such as the BRAT diet are no longer recommended. Research does not support the limiting of milk to children as doing so has no effect on duration of diarrhea. To the contrary, WHO recommends that children with diarrhea continue to eat as sufficient nutrients are usually still absorbed to support continued growth and weight gain, and that continuing to eat also speeds up recovery of normal intestinal functioning. CDC recommends that children and adults with cholera also continue to eat.

Medications such as loperamide (Imodium) and bismuth subsalicylate may be beneficial; however they may be contraindicated in certain situations.

Zinc supplementation may benefit children over six months old with diarrhea in areas with high rates of malnourishment or zinc deficiency. This supports the World Health Organization guidelines for zinc, but not in the very young.

Probiotics reduce the duration of symptoms by one day and reduced the chances of symptoms lasting longer than four days by 60%. The probiotic lactobacillus can help prevent antibiotic-associated diarrhea in adults but possibly not children. For those with lactose intolerance, taking digestive enzymes containing lactase when consuming dairy products often improves symptoms.

In the United States, biotin supplements are readily available without a prescription in amounts ranging from 1,000 to 10,000 micrograms (30 micrograms is identified as Adequate Intake).

One strategy to control the disease in areas where it is common is the treatment of entire groups of people regardless of symptoms via mass drug administration. This is often done among school-age children and is known as deworming. While testing and treating children who are infected looks like it is effective, there is insufficient evidence to conclude that routine deworming, in the absence of a positive test, improves nutrition, haemoglobin, school attendance or school performance.

For this purpose, broad-spectrum benzimidazoles such as mebendazole and albendazole are the drugs of choice recommended by WHO. These anthelminthics are administered in a single dose are safe, relatively inexpensive, and effective for several months. Mebendazole can be given with a single dose twice a day for three consecutive days. Albendazole is given at a single dose. WHO recommends annual treatment in areas where between 20 and 50% of people are infected, and a twice a year treatment if it is over 50%; and in low risk situation (i.e. less than 20% prevalence) case-by-case treatment. In addition to these, pyrantel pamoate is also equally effective on ascaris. However, it has been reported that albendazole, mebendazole, and pyrantel pamoate are not entirely effective against "T. trichiura" with single oral doses in population-based control.

In cases of coinfection, combination therapy with ivermectin and diethylcarbamazine is advocated. However coinfection with malaria and HIV, especially among African women, does not respond well to the current combination therapies. It is more pressing for trichuriasis that the recommended drugs fail to provide positive results. A novel drug tribendimidine, which was approved in China by the CCDC for human use in 2004, has been subjected to clinical trials showing that they are highly effective against major human flukes, ascaris (>90% cure rate) and hookworm (>82%); however with low cure rate for whipworm (<37%).

Since biotin is in many foods at low concentrations, deficiency is rare except in locations where malnourishment is very common. Pregnancy, however, alters biotin catabolism and despite a regular biotin intake, half of the pregnant women in the U.S. are marginally biotin deficient.

The current standard of care for Severe Early childhood caries includes restoration and extraction of carious teeth and, where possible, includes early intervention which includes application of topical fluoride, oral hygiene instructions and education.

The initial visit is important as it allows dental professionals to flag unfavourable behaviour or eating habits. This will also allow dental clinician, working in a collaborative team, to perform diagnostic testing to determine the rate and progression of the disease. This is done by performing risk assessment based on the child's age, as well as the social, behavioural, and medical history of the child. Children at low risk may not need any restorative therapy, and frequent visits should be made to detect possible early lesions. Children at moderate risk may require restoration of progressing and cavitated lesions, while white spot and enamel proximal lesions should be treated by preventive techniques and monitored for progression. Children at high risk, however, may require earlier restorative intervention of enamel proximal lesions, as well as intervention of progressing and cavitated lesions to minimize continual caries development.

As Early Childhood Caries occurs in children under the age of 5, restorative treatment is generally performed under general anaesthetic to ensure optimal results and prevent a traumatic experience for the child.

Depending on the level of cavitation of the teeth, different types of restorations may be employed. Stainless steel (preformed) crowns are pre-fabricated crown forms which can be adapted to individual primary molars and cemented in place to provide a definitive restoration.They have been indicated for the restoration of primary and permanent teeth with caries where a normal filling may not last.

Another approach of treating dental caries in young children is Atraumatic Restorative Treatment (ART). The ART is a procedure based on removing carious tooth tissues using hand instruments alone and restoring the cavity with an adhesive restorative material. This is useful to prevent trauma and requires less chair time for the young patients. This is used in cases where the teeth are being maintained in the mouth to maintain space for the future teeth to come through.

Early childhood caries can be prevented through the combination of the following: adhering to a healthy nutritional diet, optimal plaque removal, use of fluoridation on the tooth surface once erupted, care taken by the mother during the pre-natal and peri-natal period and regular dental visits. The following are recommendations to help prevent ECC.

Proton pump inhibitors (such as omeprazole and lansoprazole) and histamine H2-receptor antagonists (such as famotidine and ranitidine) are used to slow acid secretion. Once gastric acid is suppressed, symptoms normally improve.

One of the main effects of cadmium poisoning is weak and brittle bones. Spinal and leg pain is common, and a waddling gait often develops due to bone deformities caused by the cadmium. The pain eventually becomes debilitating, with fractures becoming more common as the bone weakens. Other complications include coughing, anemia, and kidney failure, leading to death.

A marked prevalence in older, postmenopausal women has been observed. The cause of this phenomenon is not fully understood, and is currently under investigation. Current research has pointed to general malnourishment, as well as poor calcium metabolism relating to the women's age.

Recent animal studies have shown that cadmium poisoning alone is not enough to elicit all of the symptoms of itai-itai disease. These studies are pointing to damage of the mitochondria of kidney cells by cadmium as a key factor of the disease.

Thoracocentesis, pericardiocentesis, pleurodesis, ligation of thoracic duct, pleuroperitoneal shunt, radiation therapy, pleurectomy, pericardial window, pericardiectomy, thalidomide, interferon alpha 2b, Total Parenteral Nutrition (TPN), medium chain triglyceride (MCT) and high protein diet, chemotherapy, sclerotherapy, transplant;

There is no standard approach to the treatment of lymphangiomatosis and treatment often is aimed at reducing symptoms. Surgical intervention may be indicated when complications arise and a number of reports of response to surgical interventions, medications, and dietary approaches can be found in the medical literature.

Unfortunately, there is no standardized treatment for lymphangiomatosis and no cure.

Treatment modalities that have been reported in the medical literature, by system, include:

Itai-itai disease was caused by cadmium poisoning due to mining in Toyama Prefecture. The earliest records of mining for gold in the area date back to 1710. Regular mining for silver started in 1589, and soon thereafter, mining for lead, copper, and zinc began. Increased demand for raw materials during the Russo-Japanese War and World War I, as well as new mining technologies from Europe, increased the output of the mines, putting the Kamioka Mines in Toyama among the world's top mines. Production increased even more before World War II. Starting in 1910 and continuing through 1945, cadmium was released in significant quantities by mining operations, and the disease first appeared around 1912. Prior to World War II, the mining, controlled by the Mitsui Mining & Smelting Co., Ltd., increased to satisfy the wartime demand. This subsequently increased the pollution of the Jinzū River and its tributaries. The river was used mainly for irrigation of rice fields, but also for drinking water, washing, fishing, and other uses by downstream populations.

Due to the cadmium poisoning, the fish in the river started to die, and the rice irrigated with river water did not grow well. The cadmium and other heavy metals accumulated at the bottom of the river and in the water of the river. This water was then used to irrigate the rice fields. The rice absorbed heavy metals, especially the cadmium. The cadmium accumulated in the people eating contaminated rice.

When the population complained to Mitsui Mining & Smelting Co. about this pollution, the company built a basin to store the mining waste water before leading it into the river. This proved ineffective, and many had already been sickened. The causes of the poisoning were not well understood and, up to 1946, it was thought to be simply a regional disease or a type of bacterial infection.

Medical tests started in the 1940s and 1950s, searching for the cause of the disease. Initially, it was expected to be lead poisoning due to the lead mining upstream. Only in 1955 did Dr. Hagino and his colleagues suspect cadmium as the cause of the disease. Toyama Prefecture also started an investigation in 1961, determining that the Mitsui Mining and Smelting's Kamioka Mining Station caused the cadmium pollution and that the worst-affected areas were 30 km downstream of the mine. In 1968, the Ministry of Health and Welfare issued a statement about the symptoms of "itai-itai" disease caused by the cadmium poisoning.

The reduction of the levels of cadmium in the water supply reduced the number of new disease victims; no new victim has been recorded since 1946. While the victims with the worst symptoms came from Toyama prefecture, the government found victims in five other prefectures.

The mines are still in operation and cadmium pollution levels remain high, although improved nutrition and medical care has reduced the occurrence of itai-itai disease.

Sick cell syndrome or cell sickness syndrome is a medical condition characterised by reduced functioning of the cellular Na+/K+ pump, which is responsible for maintaining the internal ion homeostasis. The clinical result is a rise in blood K+ level and drop of blood Na+ levels

There are a wide range of possible pathological conditions that can cause sick cell syndrome, including:

- hypoxia

- sepsis

- hypovolaemia

- malnourishment

This syndrome is well known in the field of palliative medicine as many terminal patients develop this condition.

Satoyoshi syndrome, also known as Komura-Guerri syndrome, is a rare progressive disorder of presumed autoimmune cause, characterized by painful muscle spasms, alopecia, diarrhea, endocrinopathy with amenorrhoea and secondary skeletal abnormalities. The syndrome was first reported in 1967 by Eijiro Satoyoshi and Kaneo Yamada in Tokyo, Japan. To this date, fewer than 50 cases worldwide have been reported for the Satoyoshi syndrome.

People with the syndrome typically develop symptoms of the illness at a young age, usually between the age of six and fifteen years old. The initial symptoms are muscle spasms in the legs and alopecia, also known as baldness. The spasms are painful and progressive and their frequency varies from 1 or 2 to 100 per day, each lasting a few minutes. It can be sufficiently severe to produce abnormal posturing of the affected limbs, particularly the thumbs. With progression the illness involves the pectoral girdle and trunk muscles and finally the masseters and temporal muscles. The spasms usually spare the facial muscles. Severe spasms can interfere with respiration and speech. During an attack-free period, non-stimulus-sensitive myoclonus can occur in the arms, legs and neck. Diarrhea occurs in the first 2–3 years with intolerance to carbohydrate and high glucose diets. Endocrinopathy manifests as amenorrhea and hypoplasia of the uterus. Affected children fail to attain height after 10–12 years of age.

The syndrome is not known to be a primary cause of mortality, but some patients have died as a result of secondary complications, such as respiratory failure and malnourishment.

In one 6-year-old patient antibodies to GABA-producing enzyme glutamate decarboxylase were detected.

Animal hoarding is keeping a higher-than-usual number of animals as domestic pets without ability to properly house or care for them, while at the same time denying this inability. Compulsive hoarding can be characterized as a symptom of mental disorder rather than deliberate cruelty towards animals. Hoarders are deeply attached to their pets and find it extremely difficult to let the pets go. They typically cannot comprehend that they are harming their pets by failing to provide them with proper care. Hoarders tend to believe that they provide the right amount of care for them. The American Society for the Prevention of Cruelty to Animals provides a "Hoarding Prevention Team", which works with hoarders to help them attain a manageable and healthy number of pets.

Zollinger–Ellison syndrome (ZES) is a disease in which tumors cause the stomach to produce too much acid, resulting in peptic ulcers. Symptoms include abdominal pain and diarrhea.

The syndrome is caused by a gastrinoma, a neuroendocrine tumor that secretes a hormone called gastrin. The tumor causes excessive production of gastric acid, which leads to the growth of gastric mucosa and proliferation of parietal and ECL cells.

ZES may occur on its own or as part of an autosomal dominant syndrome called multiple endocrine neoplasia type 1 (MEN 1). The primary tumor is usually located in the pancreas, duodenum or abdominal lymph nodes, but ectopic locations (e.g., heart, ovary, gallbladder, liver, and kidney) have also been described.

Another human health issue caused by animal hoarding is the risk of zoonotic diseases. Defined as "human diseases acquired from or transmitted to any other vertebrate animal", zoonotic diseases can often be lethal and in all cases constitute a serious public health concern. Examples of well-known zoonotic diseases include bubonic plague, influenza, and rabies. Common domesticated animals constitute a large portion of animals carrying zoonoses, and as a result, humans involved in animal hoarding situations are at particular risk of contracting disease. Zoonoses that may arise in hoarding situations—through vectors such as dog, cat, or rat bites—include rabies, salmonellosis, catscratch fever, hookworm, and ringworm. One zoonosis of special concern is toxoplasmosis, which can be transmitted to humans through cat feces or badly-prepared meat, and is known to cause severe birth defects or stillbirth in the case of infected pregnant women. The risk of zoonotic diseases is amplified by the possibility of community epidemics.

Viliuisk Encephalomyelitis (VE) is a fatal progressive neurological disorder found only in the Sakha (Iakut/Yakut) population of central Siberia. About 15 new cases are reported each year. VE is a very rare disease and little research has been conducted. The causative agents, origin of the disease, and involved candidate genes are currently unknown, but much research has been done in pursuit of the answers.

Those inflicted with the disease survive for a period of only a few months to several years. VE follows three main courses of infection: an acute form, a sub-acute form subsiding into a progressive form, and a chronic form. Initially, the infected patients experience symptoms such as: severe headaches, delirium, lethargy, meningism, bradykinesia, and incoordination. A small percentage of patients die during the acute phase as result of a severe coma. In all cases the disease is fatal.

Currently the mechanism of spread and infection is unknown despite the tedious epidemiological, clinical, and neurological studies that have been conducted. Recent Studies show Horizontal Disease Transmission, or the transmission of a disease from one individual to another of the same generation. It appears that VE is an infectious disease; however, the incubation period would have to be very extensive (in excess of 5 years). Many infected individuals attribute the initial symptoms as a result of a plunge in frigid waters. So far, no causative agent has been found in blood, spinal fluid, or brain tissue.