the observed link between bullous pemphigoid and neurologic disease, along with a genetic predisposition. Patients with bullous pemphigoid usually present with two or more other chronic diseases such as neurological disorders(dementia, Parkinson's disease, or stroke). However, further studies are necessary to explore the relationship between these disorders. Cause The pathogenetic mechanism of blister formation is known, the trigger to the formation of the antibodies to the hemidesmosome antigens is still unknown. Most of the bullous pemphigoid cases are due to autoantibodies (mostly IgG) directed at antigens (BP180 and BP230) arranged at the dermal-epidermal junction. However, most commonly, drug can be one of the cause of bullous pemphigoid, such as thiazide diuretics, antibiotics (e.g., penicillins, vancomycin), nonsteroidal anti-inflammatory drugs (NSAIDs) and angiotensin-converting enzyme (ACE) inhibitors (e.g., captopril) and possibly angiotensin receptor blockers (ARBs, e.g., valsartan). The implicated drugs include penicillin derivatives, sulfasalazine, ibuprofen, phenacetin, enalapril, captopril, lisinopril, gabapentin, novoscabin, levobunolol ophthalmic solution, tetracoq, influenza, tetanus, and other vaccinations, a homeopathy regimen, nifedipine, 5-aminosalicylic acid, doxazosin, serratiopeptidase, losartan, cephalexin, bumetanide, fluoxetine, chloroquine, antipsychotic drugs, enoxaparin, ciprofloxacin, furosemide (frusemide), neuroleptics, penicillamine, gliptin plus metformin, intravenous iodine, etanercept, levofloxacin, and topical fluorouracil. Influenza vaccination does not appear to be an important trigger for bullous pemphigoid. Trauma, burns, lymphedema, phototherapy, and radiation have been implicated in a very small number of cases. Pathophysiology The pathophysiology of bullous pemphigoid consists of two major components, which are immunologic and inflammatory. In the immunologic component, autoantibodies act against the hemidesmosomal bullous pemphigoid antigens BP230 (BPAg1) and BP 180(BPAg2 or type XVII collagen) which are located at the lamina lucida of the basement membrane zone. These antigens play an important role in the adhesion complexes that promote epithelial-stromal adhesion. The predominant subclass of antibodies that acts against the antigens is IgG4. IgG1 and IgG2 antibodies are less frequently detected compared to IgG4 antibodies, while IgG3 antibodies are usually absent. When the autoantibodies bind specifically to the target antigens, the complement system and mast cells are activated, thereby representing the inflammatory component. Inflammatory cells such as neutrophils and eosinophils are then attracted to the affected area. They are postulated to release proteolytic enzymes which degrade the hemidesmosomal proteins, resulting in blister formation. Other potential contributory factors including genetic factors, environmental exposures to infections and drugs as well as the phenomenon of epitope spreading are also known to cause bullous pemphigoid. Diagnosis Diagnosis of bullous pemphigoid includes clinical assessment, skin biopsy