STEPTRACKERPHARMACOLOGY | ADVERSE EFFECTS | RAPID-FIRE REVIEW

Signature Adverse Effects

One-line associations between a finding and the drug most likely to cause it — the fastest way to review before an exam. Each row links to the full page.

FOCUS ON
Most drug-toxicity questions describe the finding and expect the drug. Group them by mechanism when you can: K⁺ channel block → QT; Na⁺ channel block → wide QRS; anticholinergic → retention, delirium; D2 block → EPS, prolactin; folate antagonism → megaloblastic anemia; oxidant stress → hemolysis in G6PD; HLA-linked → SJS/DRESS. Full organ-by-organ lists: 14.03.
FINDING
DRUG
WHY
PAGE
Dry cough, angioedema
ACE inhibitors
↑ Bradykinin
3.01
Ankle edema
Dihydropyridine CCBs
Precapillary dilation
3.01
Yellow-green vision, arrhythmia
Digoxin
Na⁺/K⁺-ATPase inhibition
3.02
Pulmonary fibrosis, thyroid change, blue-gray skin
Amiodarone
Iodine, tissue deposition
3.05
Cinchonism · drug-induced lupus
Quinidine · procainamide, hydralazine
— · slow acetylation
3.04
Flushing prevented by aspirin
Niacin
Prostaglandin release
3.06
Ototoxicity + nephrotoxicity
Aminoglycosides (also loops, cisplatin, vancomycin)
Hair-cell and tubular damage
12.02
Platelets fall day 5–10, thrombosis
Heparin (HIT)
Anti-PF4 antibodies
5.01
Skin necrosis early in therapy
Warfarin
Protein C falls first
5.01
Lactic acidosis, B12 deficiency
Metformin
↓ Gluconeogenesis, ↓ B12 absorption
6.01
Agranulocytosis
Clozapine, carbamazepine, PTU/methimazole, dapsone
Idiosyncratic
10.02
Gingival hyperplasia, hirsutism
Phenytoin (also cyclosporine, CCBs)
Fibroblast stimulation
9.01
Pancreatitis, hepatotoxicity, NTDs
Valproate
Mitochondrial toxicity, folate
9.01
SJS/TEN after rapid titration
Lamotrigine
Immune reaction
9.01
Nephrogenic DI, hypothyroidism, tremor
Lithium
↓ ADH response, ↓ thyroid release
10.03
Tardive dyskinesia
Antipsychotics, metoclopramide
D2 receptor upregulation
10.02
Priapism
Trazodone
α1 blockade
10.01
Seizures in eating disorder
Bupropion
↓ Seizure threshold
10.01
Malignant hyperthermia
Inhaled anesthetics + succinylcholine
RYR1 Ca²⁺ release
9.03
Tendon rupture, QT, aortic aneurysm
Fluoroquinolones
Collagen damage, hERG block
12.03
Disulfiram-like reaction
Metronidazole (also some cephalosporins, sulfonylureas)
Aldehyde dehydrogenase block
12.03
Optic neuritis · orange fluids · neuropathy
Ethambutol · rifampin · isoniazid
— · pigment · B6 depletion
12.03
Gray baby syndrome
Chloramphenicol
Neonates lack glucuronidation
12.02
Teeth discoloration, photosensitivity
Tetracyclines
Ca²⁺ binding, phototoxicity
12.02
Rigors, ↓ K⁺, ↓ Mg²⁺, AKI
Amphotericin B
Membrane pores in tubules
12.04
Hemorrhagic cystitis · cardiomyopathy · lung fibrosis
Cyclophosphamide · doxorubicin · bleomycin
Acrolein · free radicals · free radicals
13.01
Peripheral neuropathy, constipation
Vincristine
Microtubule disruption in axons
13.01
Nephrotoxicity, gum hyperplasia after transplant
Cyclosporine
Afferent vasoconstriction
13.03
Reye syndrome · tinnitus
Aspirin
Mitochondrial injury · cochlear effect
11.01
Gynecomastia
Spironolactone, ketoconazole, cimetidine, digoxin
Antiandrogen
4.01

Mechanism — QT prolongation

Drug blocks hERG (IKr)
→
Slower repolarizationLong QT
→
Early afterdepolarizationsWorse with ↓ K⁺, ↓ Mg²⁺, bradycardia
→
Torsades de pointesIV magnesium

Hemolysis in G6PD deficiency

GROUP
DRUGS
PAGE
Antimalarials
Primaquine, tafenoquine
Antibacterials
Sulfonamides, dapsone, nitrofurantoin
Others
Rasburicase, methylene blue

How it's tested

COMMON CONFUSIONMany drugs share a toxicity — narrow the list with the patient's disease (a TB patient's neuropathy is isoniazid; a lymphoma patient's is vincristine).
THE TRAPA new symptom after a new drug is the drug until proven otherwise — and a new drug can raise an old drug's level (interaction).
YOUR APPROACHFinding → mechanism family → drugs the patient takes → most likely culprit → page for details.

If you see… think…

Red man–type flushing during infusion → vancomycin
Purple-glove syndrome → IV phenytoin
Orange urine and tears → rifampin
Vin rosé urine → deferoxamine chelating iron
Red urine (not blood) → doxorubicin, rifampin
Darkened iris → latanoprost
Phosphenes → ivabradine
Blue-tinted vision → sildenafil
Livedo reticularis → amantadine
Metallic taste → metronidazole