Meclizine vs Diphenhydramine

Meclizine vs Diphenhydramine – detailed comparison:


It is the generic name of a drug that belongs to a group of drugs called antihistamines.

It can be found under the following brand names – Antivert, Meclicot, Bonine, or Medivert.

Mechanism of Action

This medication works by blocking the response to histamine in the human body.

It was first approved by the US Food and Drug Administration in 1957.


This medication is used to treat vomiting, nausea, and dizziness brought on by motion sickness.


The usual recommended dose is 25 to 50 mg orally once a day as needed.

Side Effects and Precautions

Common side effects may include:

  • drowsiness;
  • headache;
  • tired feeling;
  • dry mouth;
  • vomiting.

Rare side effects may include:

  • swelling or red eyes;
  • a severe rash;
  • seizures;
  • a feeling like your throat is closing up;
  • Irregular heartbeat (arrhythmia);
  • a swollen tongue;
  • dizziness;
  • gums bleeding when you brush your teeth;
  • hallucinations;
  • easy bruising;
  • personality changes;
  • problems getting an erection;
  • problems urinating;
  • constipation;
  • blurred vision;
  • poor coordination;
  • excessive sleepiness.


Before taking this antihistamine, tell your doctor if you have:

  • urination problems;
  • an enlarged prostate;
  • glaucoma;
  • asthma;
  • kidney disease;
  • liver disease.


Avoid drinking alcoholic beverages while taking this antihistamine since alcohol use can substantially increase the risk of side effects.

Drug Interactions

It may negatively interact with other medications, especially:

  • Promethazine;
  • Ativan (lorazepam);
  • tramadol;
  • Benadryl (diphenhydramine);
  • Xanax (alprazolam);
  • Cymbalta (duloxetine);
  • Zyrtec (cetirizine);
  • dimenhydrinate;
  • Valium (diazepam);
  • Dramamine (dimenhydrinate);
  • Tylenol PM (acetaminophen/diphenhydramine);
  • Norco (acetaminophen/hydrocodone);
  • Lyrica (pregabalin).

Pregnancy & Breastfeeding

It is recommended that breastfeeding mothers not take this antihistamine. Also, this medication falls under the FDA’s Pregnancy Category B, which means it has not been shown to harm an unborn baby.


It is the generic name of a drug that belongs to a group of drugs called antihistamines. It can be found under the brand name of Benadryl.

Mechanism of Action

It works by blocking the effects of a natural compound that is released by the human body, called histamine.


Before using this antihistamine, tell your healthcare professional if you have:

  • an enlarged prostate;
  • an overactive thyroid;
  • increased pressure in the eye;
  • glaucoma;
  • a cough caused by emphysema;
  • blockage in your digestive tract;
  • heart disease;
  • an allergy to diphenhydramine;
  • low blood pressure;
  • kidney disease;
  • bladder obstruction;
  • a colostomy or ileostomy;
  • asthma;
  • a stomach ulcer;
  • liver disease;
  • chronic obstructive pulmonary disease.


This medication is used to treat hives, itching, a runny nose, sneezing, rashes, watery eyes, and other symptoms of seasonal or year-round allergies.

In addition, this antihistamine is used to treat motion sickness, to induce sleep, to suppress coughs, and to treat mild forms of Parkinson’s disease.

Drug Interactions

This antihistamine may interact with:

  • prednisolone acetate;
  • monoamine oxidase inhibitors;
  • potassium supplements, including – Epiklor and Polycitra;
  • over-the-counter cold medicines;
  • diazepam;
  • anxiety or sleep drugs;
  • any other drugs which make you feel drowsy or relaxed;
  • antidepressants;
  • allergy medicines.

Side Effects

Common side effects may include:

  • drowsiness;
  • constipation;
  • nausea;
  • upset stomach;
  • disturbed coordination;
  • tiredness;
  • difficulty urinating;
  • fatigue;
  • tremor;
  • enlarged prostate;
  • headaches;
  • blurred vision;
  • dry mouth;
  • dizziness;
  • loss of appetite;
  • double vision.

Pregnancy & Breastfeeding

There are no studies regarding the safe use of this antihistamine during pregnancy, hence, contact your physician before using this antihistamine if you are pregnant.

It can pass into breast milk and may affect the infant in a negative way, therefore, avoid the medication if you are breastfeeding an infant.


Note – it is not recommended to give this medication to children under 6 years.

The usual recommended dosage is 25-50 mg every 4-6 hours. The maximum recommended dosage should not exceed 400 mg per day.


Do not drink alcohol while using this antihistamine since alcohol can increase the risk of side effects.

Bottom Line – Meclizine vs Diphenhydramine

Meclizine (brand names – Antivert, Meclicot, Bonine, or Medivert) is a medication that belongs to a class of drugs called antihistamines. It is used to treat motion sickness and dizziness.

Diphenhydramine (brand name – Benadryl) is a medication that is effective in treating symptoms of mild allergy and the common cold as well as a runny nose, sneezing, hives, and itching. It is a first-generation antihistamine medicine.

In conclusion, both medications are first-generation antihistamines and have an effect in treating motion sickness. However, meclizine does not tend to make people drowsy, making it a more preferred OTC medication to control motion sickness.

Regarding their price, the average retail price for 30 tablets of meclizine 25mg is $11, while the average retail price for 30 capsules of diphenhydramine 25mg is $14.

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