Table 5. Lists of contraindicated drug interactions and most common major drug interactions with potential effects according to Micromedex Drug Interaction Database.

Drug combination	Potential effects	(n = 1360) N (%)
Contraindicated drug interactions
Haloperidol + Metoclopramide	Increased risk of extrapyramidal reaction and neuroleptic malignant syndrome	1 (0.1)
Citalopram + Metoclopramide	Increased risk of extrapyramidal reaction and neuroleptic malignant syndrome	1 (0.1)
Oxybutynin + Potassium	Increased risk of gastrointestinal lesions	1 (0.1)
Major drug interactions
Heparin + Aspirin	Increased risk of bleeding	82 (6.0)
Aspirin + Furosemide	Reduced diuretic effectiveness and possible nephrotoxicity	52 (3.8)
Polyethylene glycol + Senna	Increased risk of mucosal ulceration or ischemic colitis	39 (2.9)
Aspirin + Metformin	Increased risk of hypoglycemia	20 (1.5)
Aspirin + Digoxin	Increased serum concentration of digoxin; prolonged half-life of digoxin	17 (1.3)
Clopidogrel + Heparin	Increased risk of bleeding	14 (1.0)
Sertraline + Aspirin	Increased risk of bleeding	12 (0.9)
Citalopram + Aspirin	Increased risk of bleeding	12 (0.9)
Citalopram + Heparin	Increased risk of bleeding	12 (0.9)
Clopidogrel + Omeprazole	Reduced plasma concentrations of clopidogrel active metabolite and reduced antiplatelet activity	12 (0.9)

Data are presented as n (%).