IBUPROFEN AND DIPHENHYDRAMINE HYDROCHLORIDE
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. Diphenhydramine is an antihistamine that antagonizes histamine H1 receptors.
| Metabolism | Ibuprofen is primarily metabolized by CYP2C9. Diphenhydramine undergoes extensive first-pass metabolism via CYP2D6. |
| Excretion | Ibuprofen: Renal (90% as glucuronide conjugates, <10% unchanged). Diphenhydramine: Renal (primarily as metabolites, <10% unchanged). Both undergo hepatic metabolism with renal excretion of metabolites. |
| Half-life | Ibuprofen: 2-4 hours (immediate-release). Diphenhydramine: 8-12 hours (prolonged in hepatic impairment). |
| Protein binding | Ibuprofen: >99% bound to albumin; Diphenhydramine: 78-85% bound to plasma proteins. |
| Volume of Distribution | Ibuprofen: 0.1-0.2 L/kg (confined to plasma and interstitial fluid). Diphenhydramine: 3-8 L/kg (extensive tissue distribution). |
| Bioavailability | Ibuprofen: 80-100% (oral immediate-release). Diphenhydramine: 50-75% (oral, first-pass metabolism). |
| Onset of Action | Oral: Ibuprofen 30-60 min; Diphenhydramine 30-60 min. Onset may be slower with food. |
| Duration of Action | Ibuprofen: 4-6 hours; Diphenhydramine: 4-6 hours (up to 12 hours for sedation). |
| Molecular Weight | Ibuprofen: 206.3 Da; Diphenhydramine Hydrochloride: 291.8 Da |
| Action Class | NSAID and Antihistamine Combination |
1-2 tablets (200 mg ibuprofen/25 mg diphenhydramine HCl each) orally every 4-6 hours as needed; maximum 6 tablets in 24 hours.
| Dosage form | CAPSULE |
| Renal impairment | GFR 30-89 mL/min: No adjustment needed. GFR 15-29 mL/min: Avoid use due to diphenhydramine accumulation and ibuprofen nephrotoxicity. GFR <15 mL/min: Contraindicated. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Use with caution; reduce dose by 50% or avoid due to increased diphenhydramine sedation. Child-Pugh C: Contraindicated. |
| Pediatric use | Age ≥12 years: Same as adult dose (1-2 tablets). Age 6-11 years: Not recommended. Age <6 years: Contraindicated. |
| Geriatric use | Reduce dose to 1 tablet every 6-8 hours; maximum 3 tablets in 24 hours due to increased risk of anticholinergic effects, sedation, and renal impairment. |
| 1st trimester | Avoid; ibuprofen is associated with increased risk of miscarriage and congenital malformations; diphenhydramine has been associated with limited case reports of malformations. |
| 2nd trimester | Use with caution; ibuprofen may cause oligohydramnios and premature ductus arteriosus constriction; diphenhydramine is generally considered safe but use lowest effective dose. |
| 3rd trimester | Avoid; ibuprofen is contraindicated due to risk of premature closure of ductus arteriosus, oligohydramnios, and neonatal renal impairment; diphenhydramine may cause neonatal respiratory depression if used near term. |
Clinical note
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
| FDA category | Positive |
| Placental transfer | Both ibuprofen and diphenhydramine cross the placenta. Ibuprofen reaches approximately 1-2% of maternal serum levels; diphenhydramine reaches 10-100% depending on study. |
■ 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 increase with duration of use. NSAIDs are contraindicated in the setting of coronary artery bypass graft (CABG) surgery.
| Common Effects | fever |
| Serious Effects | Gastrointestinal bleeding, ulceration, and perforation, Cardiovascular thrombotic events (e.g., myocardial infarction, stroke), Renal impairment including acute renal failure, Anaphylactic reactions, Severe hepatic reactions including jaundice and hepatitis, Central nervous system depression (e.g., sedation, confusion, respiratory depression) |
Hypersensitivity to ibuprofen, diphenhydramine, or any componentHistory of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDsActive peptic ulcer disease or gastrointestinal bleedingSevere renal impairment (creatinine clearance <30 mL/min)Severe hepatic impairmentThird trimester of pregnancy (due to risk of premature ductus arteriosus closure)Concomitant use of other NSAIDs including aspirin (unless low-dose aspirin prescribed by physician)Treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery
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| Breastfeeding | Ibuprofen is excreted into breast milk in low amounts and is generally considered compatible with breastfeeding; diphenhydramine is also excreted but in small quantities. Monitor infant for drowsiness, irritability, or paradoxical excitation. Avoid high doses or prolonged use. |
| Lactation Rating | L2 (Ibuprofen); L3 (Diphenhydramine) |
| Teratogenic Risk | First trimester: Ibuprofen is associated with an increased risk of spontaneous abortion and congenital malformations (cardiac defects, gastroschisis) in some studies. Diphenhydramine is generally considered low risk, but some data suggest a possible increased risk of cleft palate. Second trimester: Ibuprofen is relatively low risk for major malformations; diphenhydramine is low risk. Third trimester: Ibuprofen is contraindicated due to risk of premature closure of the ductus arteriosus, oligohydramnios, and neonatal renal impairment; diphenhydramine may cause neonatal respiratory depression and withdrawal symptoms if used near term. |
| Fetal Monitoring | Monitor for oligohydramnios (via ultrasound) and ductus arteriosus constriction (via fetal echocardiography) if ibuprofen is used in third trimester. Monitor neonatal respiratory status and sedation if diphenhydramine is used near delivery. In all trimesters, assess maternal renal function and bleeding risk. |
| Fertility Effects | Ibuprofen may reversibly impair female fertility by interfering with ovulation (prostaglandin synthesis inhibition); effect resolves upon discontinuation. Diphenhydramine has no known direct effect on fertility. |
| Precautions |
| Risk of serious cardiovascular events, Risk of serious gastrointestinal bleeding, ulceration, and perforation, Avoid use in patients with known hypersensitivity to NSAIDs or diphenhydramine, May cause drowsiness and impair mental alertness, Not for use in children under 12 years of age |
| Food/Dietary | Take with food or milk to reduce GI upset. Avoid excessive alcohol consumption as it increases risk of GI bleeding and sedation. No specific food restrictions beyond general healthy diet. |
| Clinical Pearls | Ibuprofen is an NSAID that can cause GI bleeding and renal impairment; avoid in patients with severe renal disease, active peptic ulcer, or after recent GI bleeding. Diphenhydramine is an anticholinergic antihistamine that can cause sedation, confusion, and urinary retention; use caution in elderly, patients with glaucoma, or prostatic hyperplasia. The combination is commonly used for short-term relief of insomnia associated with minor aches and pains. Educate patients about not taking with other NSAIDs or antihistamines. Avoid driving or operating machinery due to sedation. |
| Patient Advice | Take only as directed for short-term sleep aid (usually no more than 10 consecutive days). · Do not exceed recommended dose; overdose may cause serious side effects. · Avoid alcohol, as it increases sedation and risk of GI bleeding. · Do not take with other products containing ibuprofen or other NSAIDs (e.g., aspirin, naproxen). · May cause drowsiness; do not drive or operate heavy machinery until you know how this medication affects you. · Avoid taking with other antihistamines (e.g., in cold or allergy medications). · Report any signs of stomach bleeding (e.g., black/tarry stools, vomit that looks like coffee grounds), difficulty urinating, or rapid heartbeat. · Store at room temperature away from moisture and heat. |