Belix Side Effects

Generic name: diphenhydramine

Medically reviewed by Drugs.com. Last updated on Oct 3, 2024.

Note: This document provides detailed information about Belix.

Applies to diphenhydramine: oral capsules and tablets, parenteral injection Side Effects associated with diphenhydramine. Some dosage forms listed on this page may not apply specifically to the brand name Belix.

Applies to diphenhydramine: oral capsules and tablets, parenteral injection.

Side effects include:

Sedation, sleepiness, dizziness, disturbed coordination, epigastric distress, thickening of bronchial secretions.

For healthcare professionals

Applies to diphenhydramine: compounding powder, injectable solution, oral capsule, oral disintegrating strip, oral liquid, oral tablet, oral tablet chewable, oral tablet disintegrating.

General adverse events

The most commonly reported side effects included somnolence, dizziness, and incoordination.^[Ref]

Nervous system

• Common (1% to 10%): Sedation/somnolence/sleepiness, drowsiness, unsteadiness, dizziness, headache, attention disturbance
• Rare (0.01% to 0.1%): Extrapyramidal effects, tremor, convulsions
• Frequency not reported: Paresthesia, dyskinesia/muscle dyskinesia, vertigo, neuritis, incoordination, psychomotor impairment, activation of epileptogenic foci^[Ref]

Drowsiness usually diminishes after a few days.^[Ref]

Gastrointestinal

• Common (1% to 10%): Dry mouth
• Frequency not reported: Gastrointestinal disturbance, nausea, vomiting, constipation, diarrhea, dyspepsia, epigastric distress^[Ref]

Other

• Common (1% to 10%): Fatigue
• Frequency not reported: Lassitude, tinnitus, acute labyrinthitis, asthenia, chills, impaired performance (including impaired driving, work, and/or information processing)^[Ref]

Psychiatric

• Rare (0.01% to 0.1%): Confusion, depression, sleep disturbances
• Frequency not reported: Paradoxical excitation/excitation, agitation, increased energy, restlessness, nervousness, euphoria, anxiety, hallucinations, insomnia, irritability^[Ref]

Cardiovascular

• Rare (0.01% to 0.1%): Palpitations, hypotension, arrhythmia
• Frequency not reported: Tachycardia, chest tightness, extrasystoles^[Ref]

Hematologic

• Rare (0.01% to 0.1%): Blood disorders
• Frequency not reported: Hemolytic anemia, thrombocytopenia, agranulocytosis^[Ref]

Hypersensitivity

• Rare (0.01% to 0.1%): Hypersensitivity reactions
• Frequency not reported: Angioedema, anaphylactic shock^[Ref]

Hepatic

• Rare (0.01% to 0.1%): Liver dysfunction^[Ref]

Dermatologic

• Frequency not reported: Rash, urticaria, skin rashes, erythema, photosensitivity, pruritus, drug rash, excessive perspiration^[Ref]

Respiratory

• Frequency not reported: Dyspnea, thickening of bronchial secretions, throat tightening, wheezing, nasal stuffiness, dry nose or throat^[Ref]

Genitourinary

• Frequency not reported: Urinary hesitancy/difficulty/retention, dysuria, early menses^[Ref]

Ocular

• Frequency not reported: Blurred vision, dry eyes, diplopia^[Ref]

Metabolic

• Frequency not reported: Increased appetite, anorexia^[Ref]

Musculoskeletal

• Frequency not reported: Muscle twitching/weakness^[Ref]

See also:

Frequently asked questions

• What are the strongest sleeping pills?
• What is the max dose of diphenhydramine for adults?
• Does Mucinex help with Covid?
• Does diphenhydramine raise blood pressure?
• Can diphenhydramine be used as a sleep aid?
• Does Benadryl help with or cause anxiety?
• Diphenhydramine Hydrochloride vs Citrate: What's the difference?

Further information

Belix side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer