A variety of inciting infections have been observed. The most common infection sites are in the upper respiratory tract: including rhinitis, sinusitis, and pharyngitis. The specific microbe most commonly recognized has been group A Streptococcus. Mycoplasma pneumonia, influenza, and other common viruses have also been noted. Influenza has often been well-documented anecdotally at both initial onset and exacerbations of PANS.

A number of additional infections, including gastrointestinal infections, dental infection, herpes simplex, varicella, Epstein-Barr virus, enterovirus, Kawasaki disease, and anaphylactoid purpura, have been mentioned to be associated with the onset or exacerbation of PANS symptoms in a small number of cases.

Additionally, studies have shown a high rate of concurrent autoimmunity in patients with PANS and their first degree family members further supporting a role for inflammation in PANS.

Brief psychotic disorder is a period of psychosis whose duration is generally shorter, is not always non-recurring, but can be, and is not caused by another condition.

The exact incidence and prevalence of brief psychotic disorder is not known, but it is generally considered uncommon. Internationally, it occurs twice as often in women than men, and even more often in women in the United States. It typically occurs in the late 30s and early 40s. The exact cause of brief psychotic disorder is not known. One theory suggests a genetic link, because the disorder is more common in people who have family members with mood disorders, such as depression or bipolar disorder. Another theory suggests that the disorder is caused by poor coping skills, as a defense against or escape from a particularly frightening or stressful situation. These factors may create a vulnerability to develop brief psychotic disorder. In most cases, the disorder is triggered by a major stress or traumatic event. Childbirth may trigger the disorder in some women. Approximately 1 in 10,000 women experience brief psychotic disorder shortly after childbirth. There are general medical causes of brief psychosis that should also be considered when being evaluated. Post-natal depression, HIV and AIDS, malaria, syphilis, Alzheimer's disease, Parkinson's disease, hypoglycaemia (an abnormally low level of glucose in the blood), lupus, multiple sclerosis, brain tumor and PANS.

The European Food Safety Authority concluded that chromium is not an essential nutrient, making this the only mineral for which the United States and the European Union disagree. The proposed mechanism for cellular uptake of Cr via transferrin has been called into question. There is no proof that chromium supplementation has physiological effects on body mass or composition, and its use as a supplement may be unsafe. A 2014 systematic review concluded that chromium supplementation had no effect on glycemic control, fasting plasma glucose levels, or body weight in people with or without diabetes.

Chromium may be needed as an ingredient in total parenteral nutrition (TPN), since deficiency may occur after months of intravenous feeding with chromium-free TPN. For this reason, chromium is added to normal TPN solutions for people with diabetes, and in nutritional products for preterm infants.

The symptoms of chromium deficiency caused by long-term total parenteral nutrition are severely impaired glucose tolerance, weight loss, and confusion. However, subsequent studies questioned the validity of these findings.

Strangling involves one or several mechanisms that interfere with the normal flow of oxygen into the brain:

- Compression of the carotid arteries or jugular veins—causing cerebral ischemia.

- Compression of the laryngopharynx, larynx, or trachea—causing asphyxia.

- Stimulation of the carotid sinus reflex—causing bradycardia, hypotension, or both.

Depending on the particular method of strangulation, one or several of these typically occur in combination; vascular obstruction is usually the main mechanism. Complete obstruction of blood flow to the brain is associated with irreversible neurological damage and death, but during strangulation there is still unimpeded blood flow in the vertebral arteries. Estimates have been made that significant occlusion of the carotid arteries and jugular veins occurs with a pressure of around , while the trachea demands six times more at approximately .

As in all cases of strangulation, the rapidity of death can be affected by the susceptibility to carotid sinus stimulation. Carotid sinus reflex death is sometimes considered a mechanism of death in cases of strangulation, but it remains highly disputed. The reported time from application to unconsciousness varies from 7–14 seconds if effectively applied to one minute in other cases, with death occurring minutes after unconsciousness.

Strangling is compression of the neck that may lead to unconsciousness or death by causing an increasingly hypoxic state in the brain. Fatal strangling typically occurs in cases of violence, accidents, and is one of two main ways that hanging may cause death (alongside breaking the victim's neck).

Strangling does not have to be fatal; limited or interrupted strangling is practised in erotic asphyxia, in the choking game, and is an important technique in many combat sports and self-defence systems.

Strangling can be divided into three general types according to the mechanism used:

- Hanging—Suspension from a cord wound around the neck

- Ligature strangulation—Strangulation without suspension using some form of cord-like object called a garrote

- Manual strangulation—Strangulation using the fingers or other extremity

Infants may develop respiratory symptoms as a result of exposure to "Penicillium", a fungal genus. Signs of mold-related respiratory problems in an infant include a persistent cough or wheeze. Increased exposure increases the probability of developing respiratory symptoms during the first year of life. Studies have indicated a correlation between the probability of developing asthma and exposure to "Penicillium".

Mold exposure has a variety of health effects, and sensitivity to mold varies. Exposure to mold may cause throat irritation, nasal stuffiness, eye irritation, cough and wheezing and skin irritation in some cases. Exposure to mold may heighten sensitivity, depending on the time and nature of exposure. People with chronic lung diseases are at higher risk for mold allergies, and will experience more severe reactions when exposed to mold. Damp indoor environments correlate with upper-respiratory-tract symptoms, such as coughing and wheezing in people with asthma.

Molds are ubiquitous, and mold spores are a common component of household and workplace dust. In large amounts they can be a health hazard to humans, potentially causing allergic reactions and respiratory problems.

Some molds produce mycotoxins that can pose serious health risks to humans and animals. "Toxic mold" refers to molds which produce mycotoxins, such as "Stachybotrys chartarum". Exposure to high levels of mycotoxins can lead to neurological problems and death. Prolonged exposure (for example, daily exposure) can be particularly harmful.

Almost all plant and animal species synthesize vitamin C. Notable mammalian exceptions include most or all of the order Chiroptera (bats), and one of the two major primate suborders, the "Anthropoidea" (Haplorrhini) which include tarsiers, monkeys, and apes, including human beings. The Strepsirrhini (non-tarsier prosimians) can make their own vitamin C, and these include lemurs, lorises, pottos, and galagos. Ascorbic acid is also not synthesized by at least two species of Caviidae, the capybara and the guinea pig. There are known species of birds and fish that do not synthesize their own Vitamin C. All species that do not synthesize ascorbate require it in the diet. Deficiency causes scurvy in humans, and somewhat similar symptoms in other animals.

Scurvy or subclinical scurvy is caused by a deficiency of vitamin C. In modern Western societies, scurvy is rarely present in adults, although infants and elderly people are affected. Virtually all commercially available baby formulas contain added vitamin C, preventing infantile scurvy. Human breast milk contains sufficient vitamin C, if the mother has an adequate intake. Commercial milk is pasteurized, a heating process that destroys the natural vitamin C content of the milk.

Scurvy is one of the accompanying diseases of malnutrition (other such micronutrient deficiencies are beriberi or pellagra) and thus is still widespread in areas of the world depending on external food aid. Although rare, there are also documented cases of scurvy due to poor dietary choices by people living in industrialized nations.