toxylact: a04ab55 Diphenhydramine combinations

The first professional lActological database in the word

Diphenhydramine combinations in ATC class A04AB55 are sedating H1‑antihistamine antiemetic preparations used mainly for nausea, vomiting and related cough, but they require particular caution in pregnancy and lactation because of maternal sedation, possible infant drowsiness and potential effects on milk production.medpedia.framar+5

ATC class and pharmacological profile

ATC A04AB55 comprises oral combination products containing diphenhydramine classified among antiemetics and drugs against nausea (A04), subgroup antihistamines (A04AB), which are used for motion sickness, vertigo, and nausea/vomiting of various origins.drugoffice+1
Diphenhydramine is a first‑generation H1 receptor antagonist with additional anticholinergic, antitussive and mild local anesthetic properties, explaining its role in drowsiness, antiemesis and the relief of irritative, spastic cough in inflammatory airway disease.pmc.ncbi.nlm.nih+2

Indications and contraindications

In A04AB55 combinations, diphenhydramine is indicated in adults and older children for the symptomatic treatment of nausea, vomiting, motion sickness and, in some formulations, for dry, spastic cough associated with inflammatory diseases of the respiratory tract.drugbank+2
These products are contraindicated in hypersensitivity to diphenhydramine or any component, acute asthma attack, phaeochromocytoma, angle‑closure glaucoma, prostatic hypertrophy with urinary retention, seizure disorders, clinically relevant hypomagnesaemia or hypokalaemia, as well as during pregnancy and breastfeeding according to local product information.medpedia.framar

Mechanism of action and interactions

Diphenhydramine blocks H1 receptors and reduces the effects of histamine in peripheral tissues and the central nervous system, producing antihistaminic, antiallergic and antiemetic effects.pmc.ncbi.nlm.nih+2
The sedative central action is potentiated by concurrent use of CNS depressants such as hypnotics, general anesthetics, opioids and centrally acting sedative antidepressants; therefore A04AB55 combinations should not be co‑administered with such agents, particularly in breastfeeding women or in patients operating machinery or driving.medpedia.framar+1

Adverse effects and toxicity

Typical adverse reactions include headache, visual disturbances, gastrointestinal complaints, hematologic changes, pronounced somnolence, impaired concentration the following day, dizziness, muscle weakness, increased intraocular pressure and psychomotor agitation.drugbank+2
Overdose or high cumulative doses can lead to anticholinergic toxicity (dry mouth, urinary retention, tachycardia, confusion, hallucinations), severe CNS depression or, paradoxically, stimulation with seizures, especially in children, requiring supportive care and monitoring of cardiovascular and neurologic status.pmc.ncbi.nlm.nih+1

Pregnancy safety

Large observational data suggest that first‑generation H1‑antihistamines, including diphenhydramine, are not associated with an increased risk of major congenital malformations when used in recommended doses during any trimester, and occasional use for nausea or allergy appears compatible with pregnancy.mothertobaby+3
However, sustained or high‑dose use in late pregnancy has been associated in case reports with uterine contractions, rare fetal demise and transient neonatal withdrawal‑like symptoms (tremors, diarrhea), so routine use of A04AB55 combinations for insomnia or chronic symptoms is discouraged and therapy should be individualized.ncbi.nlm.nih+1

Lactation safety and recommendations

Diphenhydramine passes into breast milk in small amounts, and occasional maternal doses of 25 mg or less are unlikely to cause adverse effects in healthy, full‑term breastfed infants.ncbi.nlm.nih+2
Nevertheless, sedating antihistamines increase the risk of infant drowsiness and may reduce milk supply when used regularly or at higher doses, so expert sources recommend non‑sedating alternatives such as cetirizine or loratadine whenever possible in breastfeeding women requiring antihistamine therapy.breastfeedingnetwork+3

For antiemetic indications, short‑term use of diphenhydramine combinations during lactation may be considered on a case‑by‑case basis, preferably with dosing immediately after a feed and close observation of the infant for excess sleepiness, poor feeding or changes in weight gain.nhs+3
Chronic use of A04AB55 preparations in lactating women, use in premature or medically fragile infants, or combination with other CNS depressants should generally be avoided, and specialist consultation (clinical pharmacologist, teratology service, lactation pharmacology expert) is advised.sps+3

Clinical positioning in toxicological‑lactological practice

From a toxicological‑lactological perspective, diphenhydramine combinations (A04AB55) are classified as sedating, centrally active antihistamine antiemetics that are typically “compatible with breastfeeding in occasional, low‑dose, short‑term use” but “not preferred” for regular therapy due to potential infant sedation and possible suppression of milk production.pakpeds+3
In pregnancy, particularly the first and second trimester, they may be used when benefits clearly outweigh risks, but non‑sedating antihistamines or non‑pharmacological antiemetic strategies are usually preferred, with avoidance of prolonged high‑dose use near term.goodrx+3

Recent ARTICLES

July 24

Abdominal Compartment Syndrome

PWhile the formal term and its consensus definitions were codified by the World Society of the Abdominal Compartment Syndrome (WSACS) only in the early 2000s, the physiological underpinnings have been observed for over 150 years. In 1863, the French physiologist Etienne-Jules Marey was the first to document the reciprocal relationship between intra-abdominal pressure (IAP) and respiratory function, noting that the expansion of the abdominal cavity directly impacted the efficiency of the thoracic bellows.

July 18

Assessment of Postoperative Fever

For the physician and the student of medicine, the assessment of postoperative fever is not merely a task of temperature monitoring, but a diagnostic journey that requires a nuanced understanding of immunology, physiology, and clinical timing. Guided by the principle of "Primum non nocere," this report seeks to bridge the gap between complex pathophysiological mechanisms and the empathetic care of the patient, providing a comprehensive framework for identifying, understanding, and managing this common clinical challenge.

July 14

Clinical Review of Congenital and Acquired Cystic Kidney Diseases

The healing arts, as envisioned by the ancient traditions of medicine, seek not merely the eradication of pathology but the restoration of a delicate equilibrium between the body’s internal environment and the external world. In the realm of nephrology, cystic diseases of the kidney represent a profound disruption of this balance.

Spotlight

A Comprehensive Analysis of Complement System Deficiencies in Pediatric and Adult Populations

The human immune system is a tapestry of ancient evolutionary mechanisms and highly specialized adaptive responses, woven together to maintain the delicate equilibrium of health. At the heart of this architecture lies the complement system, a complex network of over fifty proteins that function as the primordial vanguard of innate immunity. Named for its ability to "complement" the action of antibodies, this system serves as a bridge between the immediate, non-specific recognition of pathogens and the targeted, long-term memory of the adaptive immune response. However, when this sentinel falls silent due to genetic or acquired deficiencies, the result is a state of nuanced immunosuppression that significantly alters the human clinical landscape across all ages.