The classes of medications that are known to cause diarrhea are laxatives, antacids, heartburn medications, antibiotics, anti-neoplastic drugs, anti-inflammatories as well as many dietary supplements. Pathophysiology
Evolution
According to two researchers, Nesse and Williams, diarrhea may function as an evolved expulsion defense mechanism. As a result, if it is stopped, there might be a delay in recovery. They cite in support of this argument research published in 1973 that found that treating Shigella with the anti-diarrhea drug (Co-phenotrope, Lomotil) caused people to stay feverish twice as long as those not so treated. The researchers indeed themselves observed that: "Lomotil may be contraindicated in shigellosis. Diarrhea may represent a defense mechanism". Diagnostic approach
The following types of diarrhea may indicate further investigation is needed:

In infants
Moderate or severe diarrhea in young children
Associated with blood
Continues for more than two days
Associated non-cramping abdominal pain, fever, weight loss, etc. In travelers
In food handlers, because of the potential to infect others;
In institutions such as hospitals, child care centers, or geriatric and convalescent homes.A severity score is used to aid diagnosis in children.
From the treatments of Ashanthi DeSilva in 1990 which is considered gene therapys first success until 2014 around 60 patients were treated for either ADA-SCID or X-SCID using retroviruses vectors but as previously mentioned the occurrence of cases developing leukemia forced to make changes to improve safety, more recently in 2019 a new method using an altered version of the HIV virus as a lentivirus vector was reported in the treatment of 8 children with X-SCID, and in 2021 the same method was used in 50 children with ADA-SCID obtaining positive results in 48 of them.There are also some non-curative methods for treating SCID. Reverse isolation involves the use of laminar air flow and mechanical barriers (to avoid physical contact with others) to isolate the patient from any harmful pathogens present in the external environment. A non-curative treatment for patients with ADA-SCID is enzyme replacement therapy, in which the patient is injected with polyethyleneglycol-coupled adenosine deaminase (PEG-ADA) which metabolizes the toxic substrates of the ADA enzyme and prevents their accumulation. Treatment with PEG-ADA may be used to restore T cell function in the short term, enough to clear any existing infections before proceeding with curative treatment such as a bone marrow transplant. Epidemiology
The most commonly quoted figure for the prevalence of SCID is around 1 in 100,000 births, although this is regarded by some to be an underestimate of the true prevalence; some estimates predict that the prevalence rate is as high as 1 in 50,000 live births.