- Abdominal aortic aneurysm
- Abdominal pain
- Abilify
- Abortion
- ABPA (allergic bronchopulmonary aspergillosis)
- Abscess
- Absence seizures
- Abstinence, as contraception
- Abuse, sexual
- Acalculous cholecystitis
- Acanthamoeba
- Acarbose
- Accolate
- Accupril
- Acebutolol
- ACE inhibitors
- Acetaminophen
- Acetohexamide
- Achalasia
- Acid-base disorders
- Acid-fast rods, drugs for
- Acidosis
- Acinetobacter
- Aclovate
- Acne, topical antibiotics for
- Acne rosacea
- Acne vulgaris
- Acoustic neuroma (neurinoma)
- Acquired immunodeficiency syndrome (AIDS)
- Acrocyanosis
- Acromegaly & Gigantism
- Actinic keratosis
- Actinomadura
- Actinomyces, drugs for
- Actinomycetoma
- Actinomycosis
- Actos
- Acular
- Acute angle-closure glaucoma
- Acute intermittent porphyria
- Acute interstitial pneumonitis (AIP)
- Acute lymphoblastic/lymphocytic leukemia (ALL)
- Acute myelocytic/myelogenous leukemia (AML)
- Acute promyelocytic leukemia
- Acute renal failure
- Acute respiratory distress syndrome (ARDS)
- Acute respiratory distress syndrome (ARDS), disorders assicuated with
- Acute tubular necrosis
- Adalat
- Addiction
- Addison's disease
- Adenocarcinoma, gastric
- Adenocarcinoma, of small intestine
- Adenoma, liver cell
- Adenoma, villous, of small intestine
- Adenomyomatosis
- Adenosine
- Adenovirus infections
- ADH, syndrome of inappropriate
- Adjustment disorder
- Adrenal crisis
- Adrenal gland cancer, treatment of
- Adrenal insufficiency, acute
- Adrenal insufficiency, chronic
- Adrenal mass
- Adrenocortical insufficiency, acute (Adrenal Crisis)
- Adrenocortical insufficiency, chronic (Addison's Disease)
- Adrenocortical tumors, paraneoplastic syndromes with
- Adrenocorticosteroids, as anticancer agents
- Adrenoleukodystrophy
- Adult-onset diabetes
- Adult Still's disease
- Advair Diskus
- Advil
- Aedes mosquito
- Aerobic pneumonia, mixed flora
- AeroBid
- Aeromonas, traveler's diarrhea from
- African trypanosomiasis
- Agenerase
- Age-related macular degeneration
- Aggressive behavior
- Agoraphobia
- AIDS
- Airway obstruction, bronchi
- Airway obstruction, trachea
- Airway obstruction, upper
- Albumin, serum
- Albuterol
- Alclometasone dipropionate
- Alcohol abuse (alcoholism)
- Alcoholic fatty liver disease
- Alcoholic hepatitis
- Alcohol Use Disorder Identification Test (AUDIT)
- Alcohol withdrawal
- Aldactazide
- Aldesleukin
- Aldomet
- Aldosterone, excess
- Alemtuzumab
- Aleve
- Alkaline phosphatase
- Alkalosis
- Alkaptonuria
- Alkylating agents
- ALL
- Allergic Bronchopulmonary Aspergillosis (ABPA)
- Allergic disorders
- Allergic drug reactions
- Allergic rhinitis
- Allergic vasculitis
- Allopurinol
- Alomide
- Alopecia
- Alopecia areata
- Alpha-adrenoceptor blocking agents
- Alpha-glucosidase inhibitors
- Alpha particles, radiation reactions from
- alpha-thalassemia
- Alprazolam
- ALT
- Altace
- Alteplase, for acute MI
- Altered mental status
- Altered mental status in a diabetic
- Altered mental status in HIV/AIDS
- Altitude sickness
- Aluminum toxicity, in osteomalacia
- Alveolar hemorrhage, diffuse
- Alveolar hydatid disease
- Alveolar hypoventilation, primary
- Alveolitis, cryptogenic fibrosing
- Alzheimer's disease
- Amanita mushroom poisoning
- Amaryl
- Amaurosis fugax
- Ambien
- Amcinonide
- Amebiasis
- Amebic liver disease
- Amebic meningoencephalitis, primary
- Ameboma, treatment of
- Amenorrhea
- American trypanosomiasis
- Amifostine
- Amiloride, hydrochlorothiazide and
- Amiodarone
- Amitriptyline
- AML
- Amlodipine
- Amoxapine, for depression
- Amoxicillin
- Amphetamine
- Amphetamine & cocaine overdose
- Amprenavir
- Ampullary carcinoma, of small intestine
- Amylase increased
- Amyloidosis
- Amyloidosis, cancers with
- Amyotrophic lateral sclerosis (ALS)
- Anaerobic infections
- Anafranil
- Anal cancer
- Anal fissure
- Analgesic drugs
- Anaphylaxis
- Anaplastic thyroid carcinoma
- Anaprox
- Anastrozole
- Ancylostoma braziliense
- Ancylostoma caninum
- Ancylostoma duodenale
- Androgen antagonists
- Androgenetic baldness
- Androgens, as anticancer agents
- Anemia
- Aneurysm
- Angiitis, primary CNS
- Angina pectoris
- Angina Pectoris, unstable
- Angioedema & anaphylaxis
- Angioedema & urticaria
- Angiostrongyliasis cantonensis
- Angiostrongyliasis costaricensis
- Angiotensin II receptor blockers
- Angular cheilitis
- Animal bites
- Anion gap
- Anisakiasis
- Anistreplase (APSAC), for acute MI
- Ankle pain
- Ankle sprains
- Ankylosing spondylitis
- Anogenital pruritus
- Anorectal infections
- Anorectal pain
- Anorexia (poor appetite)
- Anorexia nervosa
- Anovulation
- Anovulation in reproductive years
- Ansaid
- Anserine bursitis
- Anthrax
- Antiarrhythmic agents
- Antiarthritis drugs, in breast-feeding women
- Antibiotic-associated colitis
- Antibiotics
- Anticholinergics
- Anticoagulant drugs
- Anticonvulsants
- Antidepressant drugs
- Antidiabetic drugs
- Antidiuretic hormone (ADH), syndrome of inappropriate
- Antidotes, cyanide
- Antiemetics, dosing regimens for
- Antiepileptic drugs
- Antifungals
- Antihistamine
- Antihypertensive drugs
- Antimetabolites
- Antimicrobial therapy
- Antiparkinsonian drugs, anticholinergic
- Antipruritics, dermatologic use of
- Antipsychotics
- Antiretroviral therapy
- Antisocial disorder
- Antituberculosis drugs
- Antiviral agents, topical ophthalmic
- Anxiety
- Anxiety disorders
- Anxiolytic drugs
- Aorta, coarctation of
- Aortic aneurysm, abdominal
- Aortic aneurysm, thoracic
- Aortic dissection
- Aortic insufficiency
- Aortic regurgitation
- Aortic stenosis
- Aphthous ulcer
- Aplasia
- Aplastic anemia
- Apnea, sleep, obstructive
- Appendicitis
- Apraclonidine HCl 0.5% solution
- Apraclonidine HCl 1% solution
- Apratropium bromide
- Apresoline
- Aqua glycolic
- Aquaphor
- Arbovirus encephalitides
- ARDS (acute respiratory distress syndrome)
- Arfonad
- Aripipazole
- Aromatase inhibitors
- Aromatic hydrocarbon poisoning
- Arrhenoblastoma
- Arrhythmias
- Arsenic poisoning
- Arsenic trioxide
- Arterial embolism, acute limb
- Arterial insufficiency
- Arterial thrombosis, acute limb
- Arteriovenous malformations (AVMs)
- Arteritis
- Arthritis
- Arthropan
- Arthropathy, neurogenic
- Arthropod-related skin lesions
- Asbestosis
- Ascariasis
- Ascaris lumbricoides
- Ascites
- ASD
- Asendin
- Aseptic meningitis, cerebrospinal fluid in
- Asherman's syndrome, amenorrhea in
- Asperger syndrome
- Aspergillosis
- Aspergillosis, allergic bronchopulmonary
- Aspergillus
- Aspergillus fumigatus
- Aspirated foreign body
- Aspiration, of gastric contents
- Aspiration pneumonia
- Aspiration pneumonia, drug use and
- Aspirin
- Asplenia and infection risk
- Assault, sexual
- Assisted reproductive technologies
- AST
- AST/ALT increased
- Asthma
- Astrocytoma
- Atacand
- Atacand HCT
- Ataxia
- Atenolol
- Athlete's foot
- Ativan
- ATN
- Atopic dermatitis
- Atorvastatin
- Atovaquone
- Atrial fibrillation
- Atrial flutter
- Atrial myxoma
- Atrial septal defect (ASD)
- Atrioventricular block
- Atrophic gastritis
- Atropine poisoning
- Atrovent
- Atypical absences
- Atypical mole
- Atypical nevi
- Atypical squamous cells of undetermined significance, Papanicolaou classification of
- AUDIT (Alcohol Use Disorder Identification Test)
- Auditory tube dysfunction
- Auricle diseases
- Autism
- Autism Spectrum Disorders
- Autoantibodies
- Autoimmune hemolytic anemia
- Autoimmune hepatitis
- Autoimmune thrombocytopenic purpura
- Autonomic dysfunction
- Autonomic insufficiency
- Avalide
- Avandamet
- Avandia
- Avapro
- Avascular necrosis of bone
- Aveeno
- Aventis
- Aventyl
- AVMs (arteriovenous malformations)
- AVN
- Avoidant disorder
- Azathioprine, in breast-feeding women
- Azmacort
- Azopt
- AZT