Fungal nail infections are located deep under the nail in the cuticle to which topically applied treatments are unable to penetrate in sufficient amounts. The tablets may, rarely, cause hepatotoxicity, so patients are warned of this and may be monitored with liver function tests. Alternatives to oral administration have been studied. Terbinafine may induce or exacerbate subacute cutaneous lupus erythematosus. Persons with lupus erythematosus should first discuss possible risks with their doctor before initiation of therapy. Side effects
Many side effects and adverse drug reactions have been reported with oral terbinafine hydrochloride possibly due to its extensive biodistribution and the often extended durations involved in antifungal treatment (longer than two months). A comprehensive list of adverse events associated with terbinafine use includes:

Gastrointestinal problems: Diarrhea, constipation, nausea, fullness, abdominal pain, indigestion, dyspepsia, gastritis, cholestasis, flatulence, altered stool colour, abdominal muscular pain
Central nervous system or neurological problems: Headaches, dizziness, vertigo, light-headedness, decreased concentration levels, paraesthesia (pins and needles)
Hepatic problems: Raised liver enzyme levels, liver inflammation (hepatitis), liver damage, liver failure
Immune system problems: Decreased white blood cell counts including pancytopenia, leukopenia, lymphopenia, thrombocytopenia, agranulocytosis, and neutropenia,  autoimmune reactions such as lupus erythematosus
Psychological problems: Depression, anxiety, insomnia, increased or unusual dream activity, malaise
Sensory problems: Complete loss of taste (ageusia), decreased taste (hypogeusia) and distorted taste (dysgeusia), often involving a metallic taste sensation and dry mouth, visual disturbances including blurred vision, green vision and double vision.
Although different diagnostic criteria are published, a commonly used strategy to diagnose patients is to use all three of the following:

Symptoms consistent with chronic/recurrent mast cell release:  Recurrent abdominal pain, diarrhea, flushing, itching, nasal congestion, coughing, chest tightness, wheezing, lightheadedness (usually a combination of some of these symptoms is present)
Laboratory evidence of mast cell mediator (elevated serum tryptase, N-methyl histamine, prostaglandin D2 or 11-beta- prostaglandin F2 alpha, leukotriene E4 and others)
Improvement in symptoms with the use of medications that block or treat elevations in these mediators"The World Health Organization has not published diagnostic criteria. Treatment
Common pharmacological treatments include:

Mast cell stabilizers, including cromolyn sodium and natural stabilizers such as quercetin
H1-antihistamines, such as cetirizine or ketotifen or fexofenadine or loratadine
H2-antihistamines, such as ranitidine or famotidine
Antileukotrienes, such as montelukast or zileuton as well as natural products (e.g., curcumin or St. Johns wort extracts)
Nonsteroidal anti-inflammatory drugs, including aspirin can be very helpful in reducing inflammation in some patients, while others can have dangerous reactions

Prognosis
The prognosis of MCAS is uncertain because of lack of studies. History
The condition was hypothesized by the pharmacologists John Oates and Jack Roberts of Vanderbilt University in 1991, and following a build-up of evidence featured in papers by Sonneck et al. and Akin et al., named in 2007.Diagnostic criteria were proposed in 2010 and revised in 2019. See also
FcεRI
Histamine intolerance
Immunoglobulin E

References


== External links ==