Diphenhydramine Side Effects

Brand Names: Dytuss, Sominex, Simply Sleep, Banophen, Benadryl Allergy, Ben-Tann, Benadryl, Nervine

Please note - some side effects for Diphenhydramine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Diphenhydramine - for the Consumer

Diphenhydramine/Phenylephrine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Phenylephrine:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, or throat; excitability (especially in children); headache; loss of appetite; nausea; nervousness; restlessness; trouble sleeping; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; chest pain; decreased coordination; difficulty urinating; fast or irregular heartbeat; fever; hallucinations; seizure; severe dizziness or drowsiness; severe nervousness, anxiety, restlessness, or trouble sleeping; tremors; unusual weakness.

Diphenhydramine/Ibuprofen

All medicines can cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Ibuprofen:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, throat, and nose; excitability; gas; headache; heartburn; nausea; stomach pain or upset; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; trouble breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody or black, tarry stools; change in the amount of urine produced; chest pain; confusion; dark urine; depression; fainting; fast or irregular heartbeat; fever, chills, or persistent sore throat; hallucinations; mental or mood changes; numbness of an arm or leg; one-sided weakness; red, swollen, blistered, or peeling skin; ringing in the ears; seizures; severe headache or dizziness; severe or persistent stomach pain or nausea; severe vomiting; shortness of breath; stiff neck; sudden or unexplained weight gain; swelling of hands, legs, or feet; tremor; unusual bruising or bleeding; unusual joint or muscle pain; unusual tiredness or weakness; vision or speech changes; vomit that looks like coffee grounds; wheezing; yellowing of the skin or eyes.

Diphenhydramine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine:

Dizziness; drowsiness; dry mouth, throat, and nose; thickening of mucus in nose or throat.

Severe allergic reactions (difficulty breathing; hives; itching; tightness in the chest; rash; swelling of the mouth, face, lips, or tongue); decreased alertness; excitability; fast heartbeat; hallucinations; seizures; tightness or pounding in the chest; tremor; wheezing.

Diphenhydramine/Pseudoephedrine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Pseudoephedrine:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, and throat; excitability; headache; loss of appetite; nausea; nervousness or anxiety; trouble sleeping; upset stomach; vomiting; weakness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; fast or irregular heartbeat; fever, chills, or persistent sore throat; hallucinations; mood or mental changes; persistent trouble sleeping; restlessness; seizures; severe dizziness, lightheadedness, or headache; severe drowsiness; tremor; trouble urinating or inability to urinate; unusual bruising or bleeding.

Diphenhydramine Capsules

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Capsules:

Dizziness; drowsiness; dry mouth, throat, and nose; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; decreased alertness; excitability; fast heartbeat; hallucinations; tightness or pounding in the chest; tremor; wheezing.

Diphenhydramine Chewable Tablets

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Chewable Tablets:

Dizziness; drowsiness; dry mouth, throat, and nose; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; decreased alertness; excitability; fast heartbeat; hallucinations; tightness or pounding in the chest; tremor; wheezing.

Diphenhydramine/Phenylephrine Chewable Tablets

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Phenylephrine Chewable Tablets:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, or throat; excitability (especially in children); headache; loss of appetite; nausea; nervousness; restlessness; trouble sleeping; vomiting.

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; chest pain; decreased coordination; difficulty urinating; fast or irregular heartbeat; fever; hallucinations; seizure; severe dizziness and drowsiness; severe nervousness, anxiety, or restlessness; tremors; unusual weakness.

Diphenhydramine/Pseudoephedrine Controlled-Release Capsules

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Pseudoephedrine Controlled-Release Capsules:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, or throat; excitability (especially in children); headache; loss of appetite; nausea; nervousness; restlessness; trouble sleeping; vomiting.

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; chest pain; decreased coordination; difficulty urinating; fast or irregular heartbeat; fever; hallucinations; seizure; severe dizziness and drowsiness; severe nervousness, anxiety, or restlessness; tremors; unusual weakness.

Diphenhydramine Cream

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Cream:

Skin irritation.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue).

Diphenhydramine Dispersible Tablets

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Dispersible Tablets:

Dizziness; drowsiness; dry mouth, throat, and nose; excitability; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; fast heartbeat or pounding in the chest; decreased alertness; hallucinations; tremor; wheezing.

Diphenhydramine Elixir

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Elixir:

Dizziness; drowsiness; dry mouth, throat, and nose; excitability; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; fast heartbeat or pounding in the chest; decreased alertness; hallucinations; tremor; wheezing.

Diphenhydramine/Pseudoephedrine Liquid

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Pseudoephedrine Liquid:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, and throat; excitability; headache; loss of appetite; nausea; nervousness or anxiety; trouble sleeping; upset stomach; vomiting; weakness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; fast or irregular heartbeat; fever, chills, or persistent sore throat; hallucinations; mood or mental changes; persistent trouble sleeping; restlessness; seizures; severe dizziness, lightheadedness, or headache; severe drowsiness; tremor; trouble urinating or inability to urinate; unusual bruising or bleeding.

Diphenhydramine/Phenylephrine Liquid

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Phenylephrine Liquid:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, or throat; excitability (especially in children); headache; loss of appetite; nausea; nervousness; restlessness; trouble sleeping; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; chest pain; decreased coordination; difficulty urinating; fast or irregular heartbeat; fever; hallucinations; seizure; severe dizziness or drowsiness; severe nervousness, anxiety, or restlessness; tremors; unusual weakness.

Diphenhydramine Lotion

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Lotion:

Skin irritation.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue).

Diphenhydramine Orally Disintegrating Strips

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Orally Disintegrating Strips:

Dizziness; drowsiness; dry mouth, throat, and nose; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; decreased alertness; excitability; fast heartbeat; hallucinations; tightness or pounding in the chest; tremor; wheezing.

Diphenhydramine Solution

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Solution:

Dizziness; drowsiness; dry mouth, throat, and nose; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; decreased alertness; excitability; fast heartbeat; hallucinations; pain, redness, or swelling at the injection site; tightness or pounding in the chest; tremor; wheezing.

Diphenhydramine/Phenylephrine Strips

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Phenylephrine Strips:

Constipation; diarrhea; dizziness; drowsiness; dry mouth; excitability; headache; loss of appetite; nausea; nervousness or anxiety; trouble sleeping; upset stomach; vomiting; weakness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; difficulty urinating or inability to urinate; fast or irregular heartbeat; hallucinations; mood or mental changes; persistent trouble sleeping; restlessness; seizures; severe dizziness, lightheadedness, or headache; severe drowsiness; tremor.

Diphenhydramine Suspension

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine Suspension:

Dizziness; drowsiness; itching; dry mouth, throat, and nose; excitability; thickening of mucus in nose or throat.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); convulsions; fast heartbeat or pounding in the chest; decreased alertness; hallucinations; tremor; wheezing.

Diphenhydramine/Phenylephrine Suspension

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Phenylephrine Suspension:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, or throat; excitability (especially in children); headache; loss of appetite; nausea; nervousness; restlessness; trouble sleeping; vomiting.

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; chest pain; decreased coordination; difficulty urinating; fast or irregular heartbeat; fever; hallucinations; seizure; severe dizziness and drowsiness; severe nervousness, anxiety, or restlessness; tremors; unusual weakness.

Diphenhydramine/Hydrocodone/Phenylephrine Syrup

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Hydrocodone/Phenylephrine Syrup:

Dizziness; drowsiness, excitability; headache; nausea; nervousness or anxiety; trouble sleeping; weakness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); difficulty urinating; fast or irregular heartbeat; hallucinations; seizures; severe dizziness, lightheadedness, or headache; severe drowsiness; tremor.

Diphenhydramine/Pseudoephedrine Tablets

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Diphenhydramine/Pseudoephedrine Tablets:

Constipation; diarrhea; dizziness; drowsiness; dry mouth, nose, and throat; excitability; headache; loss of appetite; nausea; nervousness or anxiety; trouble sleeping; upset stomach; vomiting; weakness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; fast or irregular heartbeat; fever, chills, or persistent sore throat; hallucinations; mood or mental changes; persistent trouble sleeping; restlessness; seizures; severe dizziness, lightheadedness, or headache; severe drowsiness; tremor; trouble urinating or inability to urinate; unusual bruising or bleeding.

Side Effects by Body System

Nervous system

Nervous system side effects have been reported frequently. These have included depression with drowsiness and sedation in nearly all patients treated. Motor skills may be impaired. Dystonic reactions have been reported after single doses of diphenhydramine.

The CNS depressant effect of diphenhydramine parallels its plasma concentrations. The plasma concentration threshold for sedation is 30 to 42 ng/mL, and to cause mental impairment is 58 to 74 ng/mL. Patients should be warned against driving while taking diphenhydramine.

Dystonic reactions have been accompanied by dizziness, mental confusion, rigidity, lip and tongue protrusion, trismus, torticollis, and swallowing difficulties and generally resolve spontaneously. Toxic encephalopathy has been reported in a child with chicken pox treated generously with topical diphenhydramine.

Delirium has been reported in elderly patients with mild dementia following a small oral dose of diphenhydramine.

Hypersensitivity

Hypersensitivity side effects have included rash, pruritus and eczema. Photosensitivity reactions have also been reported.

Most commonly, hypersensitivity has manifested itself in patients receiving systemic drug after being sensitized to it by topical application. Sensitization with systemic administration has also been reported.

Gastrointestinal

Gastrointestinal side effects have been usually mild and included nausea and dry mouth.

Cardiovascular

Cardiovascular side effects have included hypotension, tachycardia, and palpitations.

Ocular

Ocular side effects have included blurred vision, diplopia, and dry eyes due to anticholinergic effects.

Genitourinary

Genitourinary side effects have included urinary retention and dysuria as a result of the anticholinergic effects of diphenhydramine.

Hematologic

Hematologic side effects such as hemolytic anemia, thrombocytopenia, and agranulocytosis have been rarely caused by antihistamines.

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