IBUPROFEN AND DIPHENHYDRAMINE CITRATE
Clinical safety rating: avoid
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin synthesis and thereby decreasing pain, fever, and inflammation. Diphenhydramine citrate is an antihistamine that antagonizes histamine H1 receptors, producing sedative and anticholinergic effects.
| Metabolism | Ibuprofen is primarily metabolized by CYP2C9 and to a lesser extent by CYP2C8. Diphenhydramine is metabolized primarily by CYP2D6 and to a lesser extent by CYP1A2, CYP2C9, and CYP2C19. |
| Excretion | Ibuprofen: renal elimination of metabolites (approximately 90%) and unchanged drug (approximately 10%); fecal elimination <5%. Diphenhydramine: primarily renal elimination (approximately 60-70% as metabolites, 1-2% unchanged); fecal elimination approximately 10-15%. |
| Half-life | Ibuprofen: terminal elimination half-life approximately 1.8-2.5 hours in adults; prolonged in elderly and patients with hepatic impairment. Diphenhydramine: terminal elimination half-life ranges from 4 to 10 hours (mean 7 hours); may be prolonged in elderly and hepatic impairment. |
| Protein binding | Ibuprofen: extensively bound to albumin (approximately 99%). Diphenhydramine: approximately 80-85% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Ibuprofen: volume of distribution approximately 0.1-0.2 L/kg in adults; lower in neonates. Diphenhydramine: volume of distribution approximately 4-5 L/kg; extensive tissue distribution. |
| Bioavailability | Ibuprofen: oral bioavailability approximately 75-85% (immediate-release). Diphenhydramine: oral bioavailability approximately 50-60% due to first-pass metabolism. |
| Onset of Action | Ibuprofen: oral onset of analgesia within 30-60 minutes; antipyretic effect within 1-2 hours. Diphenhydramine: oral onset of sedation within 30-60 minutes; peak effect at 1-3 hours. |
| Duration of Action | Ibuprofen: analgesic and antipyretic duration 4-6 hours; anti-inflammatory effect longer with repeated dosing. Diphenhydramine: sedative effect lasts 4-6 hours; antihistaminic effect up to 24 hours. |
Ibuprofen 200 mg + Diphenhydramine citrate 38 mg (equivalent to diphenhydramine HCl 25 mg) orally every 4-6 hours as needed, not to exceed Ibuprofen 1200 mg/day or Diphenhydramine citrate 152 mg/day.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in severe renal impairment (eGFR <30 mL/min/1.73 m²). For moderate (eGFR 30-59): use lowest effective dose and monitor renal function; avoid prolonged use. For mild (eGFR 60-89): no adjustment necessary. |
| Liver impairment | Avoid in severe hepatic impairment (Child-Pugh C). For moderate (Child-Pugh B): use caution, reduce dose, and monitor. For mild (Child-Pugh A): no adjustment needed. |
| Pediatric use | For children ≥12 years: Ibuprofen 200 mg + Diphenhydramine citrate 38 mg orally every 6 hours as needed, not to exceed Ibuprofen 800 mg/day. Not recommended for children <12 years. |
| Geriatric use | Use lowest effective dose for shortest duration. Start with Ibuprofen 200 mg + Diphenhydramine citrate 19 mg (half tablet) every 6 hours as needed. Monitor renal function and for CNS effects (e.g., drowsiness, confusion). Maximum Ibuprofen 800 mg/day. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
| FDA category | Positive |
| Breastfeeding | Ibuprofen transfers into breast milk at low levels (M/P ratio 0.01-0.1); considered compatible. Diphenhydramine citrate is excreted in breast milk (M/P ratio unknown); large doses may cause sedation or irritability in infants. Caution advised with prolonged use. |
| Teratogenic Risk |
■ FDA Black Box Warning
NSAIDs cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. Risk may be increased in patients with existing cardiovascular disease or risk factors. NSAIDs are also contraindicated for the treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
| Common Effects | fever |
| Serious Effects |
Hypersensitivity to ibuprofen, diphenhydramine, or any component; history of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs; perioperative pain in CABG surgery; advanced renal disease; active GI bleeding or peptic ulcer disease; neonates (due to risk of kernicterus); concomitant use of other NSAIDs or anticoagulants without monitoring.
| Precautions | Cardiovascular thrombotic events; gastrointestinal bleeding, ulceration, and perforation; hypertension; renal toxicity; anaphylactic reactions; serious skin reactions (e.g., Stevens-Johnson syndrome); drug interaction with anticoagulants; avoidance in late pregnancy; sedation and impaired alertness (due to diphenhydramine). |
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| First trimester: NSAIDs (ibuprofen) are associated with increased risk of miscarriage and congenital anomalies (cardiac defects, gastroschisis). Diphenhydramine has weak associations with cleft palate. Second trimester: Ibuprofen may cause fetal renal dysfunction and oligohydramnios; diphenhydramine risks are low. Third trimester: Ibuprofen risks premature closure of ductus arteriosus, oligohydramnios, and necrotizing enterocolitis; diphenhydramine may cause neonatal respiratory depression and withdrawal. |
| Fetal Monitoring | Monitor fetal ultrasound for oligohydramnios and ductus arteriosus patency with ibuprofen use after 20 weeks gestation. Monitor for maternal bleeding time, platelet function, and renal function. For diphenhydramine, observe neonatal sedation and respiratory status if used near term. |
| Fertility Effects | NSAIDs (ibuprofen) can reversibly impair female fertility by inhibiting ovulation via prostaglandin synthesis inhibition. Diphenhydramine may have anticholinergic effects on cervical mucus; overall impact on fertility is minimal. |