Zzzquil vs Benadryl – Uses, Side Effects, Differences

Zzzquil is a brand name of an over-the-counter medication used as a sleep remedy. Its main active ingredient is diphenhydramine HCl, a first-generation H1-antihistamine.

It works by blocking a certain natural substance – histamine (a chemical involved in the proper digestion, immune system, and central nervous system) which the body makes during an allergic reaction.

Note – anticholinergic and sedative effects become prominent in people who overdose on this drug.


This medication is commonly used for the relief of occasional sleeplessness, especially if you have difficulty falling asleep.

Moreover, it is used alone or with other drugs to treat muscle stiffness and shaking caused by Parkinson’s disease (a long-term degenerative disorder of the central nervous system) as well as to treat and prevent vomiting, nausea, and dizziness caused by motion sickness.


The usual recommended dose is 50mg at bedtime. It is not intended to use for children under 12 years old.

Side  Effects And Precautions Of Diphenhydramine

Common side effects may include:

  • dizziness;
  • confusion;
  • upset stomach;
  • clumsiness;
  • headaches;
  • drowsiness;
  • hyperactivity;
  • increased pressure within the eye;
  • constipation;
  • sweating;
  • dry nose or mouth;
  • erectile dysfunction;
  • light sensitivity;
  • irregular heart rate;
  • blurry vision;
  • low blood pressure;
  • difficulty urinating;
  • thick lung secretions.

Rare side effects may include:

  • agitation;
  • sleepiness;
  • severe drowsiness;
  • tremors;
  • coma;
  • nervousness;
  • delirium;
  • hallucinations;
  • seizures;
  • feeling unsteady.

Before using this medication, tell your doctor if you have:

  • allergy to any medicine;
  • cardiovascular disease;
  • hyperthyroidism;
  • prostate problems;
  • glaucoma (a serious condition that damages the optic nerve, which is crucial to good vision);
  • chronic obstructive pulmonary disease;
  • asthma (a chronic disease that causes the airways to become inflamed);
  • GI obstruction;
  • bladder neck obstruction.

This sleep medicine can cause drowsiness, therefore, be careful when operating with machinery or driving a motor vehicle. Moreover, avoid consuming alcoholic beverages and other drugs.

Do not use this drug with any other medications containing diphenhydramine. Stop using this drug if sleeplessness persists for more than 14 days.


It is the trade name for the generic drug called diphenhydramine, an antihistamine that can be used to help you relax and fall asleep.

Diphenhydramine is also used to relieve symptoms of hay fever (a form of inflammation in the nose that happens when the immune system overreacts to allergens), allergy, and the common cold.

This drug works by blocking the effects of histamine, a compound released by the human body which causes many of the symptoms of allergies.


It is typically used to treat motion sickness, suppress coughs, treat mild forms of Parkinson’s disease, and induce sleep.

Furthermore, it is used to treat a runny nose, sneezing, watery eyes, itching, rashes, hives, itching, and other signs and symptoms of allergies.


The usual recommended dose is 25-50 mg every 4-6 hours. The total dose should not exceed 400 mg per day. It is not recommended for use in children under 6 years.

Side Effects And Precautions

Common side effects may include:

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

Before using this drug, tell your healthcare provider if you have:

  • an allergy to diphenhydramine;
  • a stomach ulcer;
  • increased pressure in the eye;
  • glaucoma;
  • an overactive thyroid;
  • blockage in your digestive tract;
  • a colostomy or ileostomy;
  • kidney disease;
  • chronic obstructive pulmonary disease;
  • liver disease;
  • bladder obstruction;
  • asthma;
  • an enlarged prostate;
  • low blood pressure;
  • a cough caused by emphysema (a progressive disease of the lungs which causes shortness of breath due to over-inflation of the alveoli), smoking, or chronic bronchitis;
  • heart disease.

Also, inform your doctor if you take any potassium supplements, including – Epiklor, Cytra,  K-Phos, K-Lyte, Klor-Con, Kaon, Urocit-K, and Polycitra.

Use caution while operating machinery, driving, or performing other activities when using this medicine since it may cause drowsiness or dizziness.

Drug Interactions

More importantly, it may interact with:

  • any other drugs which make you feel sleepy, drowsy, or relaxed.
  • antidepressants;
  • anxiety or sleep drugs;
  • over-the-counter cold, cough, and allergy medicines;
  • monoamine oxidase inhibitors (they elevate the levels of serotonin, norepinephrine, and dopamine in the body).

This drug may also have addictive effects, especially for people who use it in long term. Signs of addiction may include:

  • unusual euphoria;
  • impaired memory;
  • inability to focus;
  • uncoordinated movements;
  • slurred speech.

Zzzquil vs Benadryl – Which Is Better For Sleep?

Both these medications contain the same main active ingredient, called – diphenhydramine, which blocks the actions of histamine. They have the same effects, but only one difference – Zzzquil is more expensive.

These medicines are not a long-term fix for insomnia since the body can quickly build up a tolerance. Therefore, the longer you take it, the less likely it will help you fall asleep.

More importantly, if you stop using these drugs abruptly, you may experience withdrawal symptoms, like – sweating, nausea, and shaking.

5 Natural Insomnia Remedies

#1 Chamomile

Chamomile (scientific name – Matricaria recutita) has been used for millennia as an herbal sleep aid. It is a very gentle medicinal herb and can be used safely both for children and adults.

Chamomile has the ability to lower stress levels, protect the skin, soothe menstrual symptoms, and regulate sleep.

#2 Passionflower

It is a flowering shrub that produces a fleshy fruit.

According to research, sleep quality is improved in people who consumed a tea from passionflower compared with people who didn’t regularly use this tea.

#3 Kava Kava

When used as a natural sleep aid, it helps to relax the body as well as it can enhance dreaming and impart a naturally calm feeling.

#4 Valerian

This root has been used to treat problems with sleep for centuries. It reduces anxiety and stress levels. It is believed to work by increasing GABA levels, a calming neurotransmitter.

Also, it is available in supplement form or it can be made into a tea. In addition, it is commonly combined with lemon balm, hops, or other medicinal herbs which also cause drowsiness.

#5 Magnesium-Rich Foods

Magnesium is an essential mineral required for every cell of the human body. Magnesium also helps in relaxing the muscles and calming the nerves, which in turn can help people to fall asleep.

Foods high in magnesium include:

  • oat bran;
  • spirulina;
  • hazelnuts;
  • quinoa;
  • mung beans;
  • lima beans;
  • wild rice;
  • red kidney beans;
  • lentils;
  • broccoli;
  • cauliflower;
  • pecans;
  • walnuts;
  • chickpeas.

Images credit – Shutterstock & Getty

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