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Doctor insights on: Does Benadryl Cause Drowsiness

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Why does Benadryl (diphenhydramine) causes drowsiness?

Why does Benadryl (diphenhydramine) causes drowsiness?

Enters the brain: The molecular structure of benedryl allows it to enter the brain where it can interfere with the chemicals that transfer messages between brain cells. In most people it causes drowsiness, in some it will cause the opposite. Newer antihistamines like loritadine & fexofinadine have molecular structures that prevent entry into the brain, so they don't make you drousy. ...Read more

Dr. John Chiu
1,049 Doctors shared insights

Diphenhydramine (Definition)

Diphenhydramine is a sedating antihistamine which is a kind of antihistamine type drug (common ...Read more


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Can extra strength Benadryl (diphenhydramine) gel cause drowsiness?

Can extra strength Benadryl (diphenhydramine) gel cause drowsiness?

Very unlikely: Unless you are covering a large area for an extended period of time or areas with breaks in the skin, it's highly unlikely this would be absorbed systemically to cause drowsiness. ...Read more

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I was wondering: if Benadryl (diphenhydramine) only works for 4 hours and it also causes drowsiness, why people use it during the day? That seems dangerous...

Yes, it is: The trouble is that almost any drug has a variable effects from person to person. Some people can get away with using it for their symptoms without becoming drowsy. If you experience drowsiness from the use of this drug, it should not be taken in daytime ...Read more

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What can I do, besides taking benadryl, (diphenhydramine) to treat hives. Ate something that caused my body to break out in hives. Don't want to go to work drowsy. Help!

What can I do, besides taking benadryl, (diphenhydramine) to treat hives. Ate something that caused my body to break out in hives. Don't want to go to work drowsy. Help!

Hives: Non drowsy antihistamines like Allegra (fexofenadine) can help, not usre if it is food that is causing your symptoms if they are persistent, you may want to consider seeing an allergist if theybpersist. ...Read more

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What causes paradoxical reactions to benadryl (diphenhydramine). What mechanism ocurrs in the brain that makes the person stimulated rather than drowsy?

What causes paradoxical reactions to benadryl (diphenhydramine). What mechanism ocurrs in the brain that makes the person stimulated rather than drowsy?

Unknown: I've never read an explanation. I'm sure there is one published but I doubt it's proven. It tends to happen more in children thus suggesting that there is inhibition of a disinhibitor. (i.E, mumbo-jumbo!). More to the point: if it happens to you, avoid further use. ...Read more

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Besides doxylamine & diphenhydramine, what other OTC antihistamines cause drowsiness? Without a prescription.

Besides doxylamine & diphenhydramine, what other OTC antihistamines cause drowsiness? Without a prescription.

Allegra (fexofenadine): All antihistamines especially the first generation ones (benadryl, bromchlorpheniramine, CTM) can cause drowsiness when given in sufficient doses. Zyrtec (cetirizine) at the recommended dose and Loratadine at 2x the recommended dose can cause drowsiness in some people. The least likely AH to cause drowsiness is fexofenadine (Allegra). ...Read more

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Where can I buy Non drowsy Benadryl (diphenhydramine)?

Where can I buy Non drowsy Benadryl (diphenhydramine)?

Oxymoron: Benadryl (diphenhydramine) is Benadryl (diphenhydramine) which is often associated with drowsiness although not everyone is affected to the same extent. ...Read more

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When does Benadryl (diphenhydramine) drowsiness wear off?

When does Benadryl (diphenhydramine) drowsiness wear off?

Benadryl (diphenhydramine): Depending on age, weight, how much you take the effect of drowsiness can wear off at different intervals. Also depends on what other meds you take, including other otc such as coffee. ...Read more

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Benadryl (diphenhydramine) has effect on me -- drowsiness?

Common effect: Benedryl is one of the most common products in over the counter sleep aids. It works quickly & well for allergies, but if you read the small print on most bottles it warns you of this effect. Occasionally some people get the opposite effect & get hyper on it, but that is far less common than the sedation. It actually enters your brain & messes with the neuro-transmitters. ...Read more

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How long does drowsiness generally last after a benadryl (diphenhydramine)?

Four to six hours: The half life of Benadryl (diphenhydramine) is about four to six hours and usually the sedation will wear off within that time frame. As one continues to use it often a certain amount of tolerance develops and less sedation is appreciated. Studies have shown that its effect on brain function still continues despite less sedation. ...Read more

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Please let me know if there is anything that contains the same ingredients that Benadryl (diphenhydramine) has but its non drowsy?

Antihistamine: Benadryl (diphenhydramine) is the first generation antihistamine that has anticholinergic property and crosses the blood-brain barrier causing drowsiness. Several other second generation antihistamine works well and does not cause drowsiness like zyrtec, allergra and claritin. ...Read more

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How long does Benadryl (diphenhydramine) keep you drowsy?

Benadryl (diphenhydramine): Most people it will last 8 hours or so but I have seen people who still feel groggy 12 hours later or more ...Read more

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What can u take if Benadryl (diphenhydramine) makes you drowsy?

What can u take if Benadryl (diphenhydramine) makes you drowsy?

Benadryl (diphenhydramine) drowsiness: If Benadryl (diphenhydramine) makes you drowsy, use a less sedating antihistamine like allegra, zyrtec or claritin. ...Read more

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How long does it take for Benadryl (diphenhydramine) to make you drowsy?

How long does it take for Benadryl (diphenhydramine) to make you drowsy?

About 45 minutes: Benadryl (diphenhydramine) can make some people drowsy. The maximum effect occurs in about 45 minutes or so. However, it can result in hyperalertness in some people. ...Read more

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I take 2 25mg benadryl (diphenhydramine) but I get to drowsy can I take 1 & a half?

Sure: Usually Benadryl (diphenhydramine) and its generic equivalent comes in a capsule which can't be split, but you could always empty the capsule and only take half the contents. You can also try just 1 capsule or use the liquid form. 10ml of liquid contains 25mg. ...Read more

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Can you tell me when does the drowsy feeling of Benadryl (diphenhydramine) go away?

A few hours: Benadryl (diphenhydramine) is a short-acting medication, so I would expect it to go away within 4-6 hours in most people, although some people are just in general a lot more sensitive to it and experience drowsiness for a longer period. If you're having problems, you might get tablets or liquid and try taking half of what you usually take (half a tab or 1 tsp of liquid is 12.5 mg instead of 25 mg in a whole tab/cap. ...Read more

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I took 1 25mg benadryl (diphenhydramine) nd I feel the effect but if I take 2 it makes me to drowsy I wanted to know if I can take half of 1?

I took 1 25mg benadryl (diphenhydramine) nd I feel the effect but if I take 2 it makes me to drowsy I wanted to know if I can take half of 1?

Of course: Everyone responds to things differently. There is no "perfect" dose for everyone. Don't take a dose of anything that makes you feel worse. Adjust the dose to what works for you. Take the lowest effective dose. ...Read more

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Benadryl (diphenhydramine) makes me drowsy. If I take the recommended dose of Benadryl (diphenhydramine) allergy ultratabs (25mg) for my flight will that be okay?

Benadryl (diphenhydramine) makes me drowsy. If I take the recommended dose of Benadryl (diphenhydramine) allergy ultratabs (25mg) for my flight will that be okay?

Are you the pilot?: Make sure you tell the flight attendant to wake you up if you are flying and need top switch planes. Don't take Benadryl (diphenhydramine) if you are planning on driving or piloting a plane if it makes you sleepy. ...Read more

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Benadryl (diphenhydramine) for my three kids 8 9 and 4 when will they start to feel the effect of drowsiness. I will be giving them Benadryl (diphenhydramine) on the plane to help sleep?

Benadryl (diphenhydramine) for my three kids 8 9 and 4 when will they start to feel the effect of drowsiness. I will be giving them Benadryl (diphenhydramine) on the plane to help sleep?

Benedryl: Sedation will typically start 20-30 minutes after the dose. If giving a weight appropriate dose, it should be safe to give prior to the flight. However, some children have a paradoxical reaction to antihistamines, causing them to be hyperactive. You might want to think about that if you've never given your child Benedryl before. Have a great flight! ...Read more

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Does Benadryl (diphenhydramine) anti itch cream make you drowsy?

No it does not: No there is not enough absorption to make you drowsy unless used in very large body surface area. ...Read more

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Can I take benadryl, (diphenhydramine) buspirone, and sertraline together? Before bed? I know it will probably increase drowsiness, I just want to make sure it's safe.

Not a good idea: It is usually not a good idea to take several medications with similar (but not identical) actions without a doctor's supervision. One may get away with it, but then why take a chance? ...Read more

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If I become resistant to effects of diphenhydramine drowsiness, can I switch to doxylamine, or am I resistant to that too since they're similar drugs?

If I become resistant to effects of diphenhydramine drowsiness, can I switch to doxylamine, or am I resistant to that too since they're similar drugs?

You can switch.: They are different drugs so I would suspect you will be sedated by the doxylamine in spite of prior Benadryl (diphenhydramine) use. Best wishes. ...Read more

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How long does diphenhydramine stay in your system? I took 100mg before sleep, but 12 hours later, I'm still drowsy. The more dosage, the longer?

Takes a while: It sounds like it is still in your system. The half life varies quite a bit from person to person although some sources will describe a half life of around seven hours. That means that seven hours later you can still have half of the medicine in your body. As you can see, you are probably going to need more time to clear it. Stay safe! ...Read more

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How long before Benadryl (diphenhydramine) sleepiness wears off?

Hangover: So this depends on a lot of things. Typically I tell people between 12-18 hours if they are overall healthy (remember it is a medication that could be dosed every 6 hours!). Realistically may be more like 24+ hours especially if other medications are being used or someone is older. ...Read more

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Can drowsiness caused by antihistamines be treated or minimized at a necesary event?

Can drowsiness caused by antihistamines be treated or minimized at a necesary event?

Yes but: A decongestant is often added to antihistamine and would counteract some of the drowsy effects but that is not a good solution. There are at least two other non-drowsy antihistamines available and steroid nasal spray actually works far better without the drowsy effect. If your only choice is a sedating antihistamine, take it an hour before you go to bed instead of the morning. ...Read more

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Does nasalcrom (cromolyn) cause drowsiness like some antihistamines do?

Does nasalcrom (cromolyn) cause drowsiness like some antihistamines do?

Not usually: Nasalcrom is not an antihtistamine. It is a nasal topical formulation of cromolyn, which is a mast-cell stabilizer. Essentially interfering with the release of histamine as well as other inflammatory mediators from the mast cell. ...Read more

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Why does drowsiness occur after taking antihistamines?

Why does drowsiness occur after taking antihistamines?

Complex: Histamine is a wake promoting neurotransmitter in the brain. Older antihistamines like Benadryl (diphenhydramine) cross into the brain and block this center allowing for drowsiness to occur. The newer antihistamines like alleges, claritin, zyrtec do not cross as easily and are less likely to promote drowsiness. ...Read more

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Why do some antihistamines make me drowsy?

Cross into brain: Older antihistamines, such as diphenhydramine, or chlorpheniramine, actually cross the barrier between the bloodstream and the brain. This causes many people to feel drowsy or sedated. It can make some people irritable, or even cause insomnia. For this reason, the "non-sedating" antihistamines were developed. These medications cause much less drowsiness, and are better tolerated. ...Read more

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How much time until benedryl drowsiness wears off?

Typically about four: Hours, but that depends on how much one has taken, and let's face it, we all have different rates of metabolism. ...Read more

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Bitten by unknown insect. Redness and swelling to forarm. Marked with pen and doubled in size over 36hrs. Taking non drowsy antihistamines and icing?

Ice: Benadryl (or your choice of a non-sedating antihistamine such as Zyrtec, Claritin, or Allegra), ice, and ibuprofen is a good initial treatment for insect bites. Infection is a possible delayed complication. If you develop a boil, a discolored blister, fever, increasing pain, or other concerning signs, see a physician for an exam. ...Read more

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Do histamines (not antihistamine medications) make you drowsy? Antihistamines (no decongestants added) seem to make me more alert when allergies flare

Yes: Histamine is a substance released during an allergic attack and can cause drowsiness. Some of the older generation anti-histamine agents (like benedryl) can cause drowsiness because they can pass the "blood brain" barrier and cause a direct effect on thinking. In rare cases in adults, antihistamines can cause agitation. ...Read more

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Zyrtec (cetirizine) makes me very drowsy. Is this common and are there non-drowsy antihistamines that provide as effective allergy relief? Thanks

Yes: This is a common side effect of Zyrtec, but it is different for everyone. If Zyrtec makes you drowsy, you could try the other 2 common anti-histamines instead - Allegra or Claritin (loratadine). Some people have been drowsy with these medicines as well, but others have not. Best wishes. ...Read more

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I am sneezing, feeling weeuk, congested nose and tiered. No fever and its third day. Took benedryl for but it makes me too drowsy. What should I do?

I am sneezing, feeling weeuk, congested nose and tiered. No fever and its third day. Took benedryl for but it makes me too drowsy. What should I do?

Rest and Hydration: Most likely a viral upper respiratory tract infection with increased congestion and fatigue. These can last for days to over a week and are often not associated with fevers. Symptomatic management is key with lots of hydration, rest, and NSAIDs for any headaches or pain. If these symptoms are recurrent or seasonal in nature you could be suffering from allergies and likely require Allergy workup. ...Read more

Benadryl (Definition)

Diphenhydramine is a sedating antihistamine which is a kind of antihistamine type drug (common ...Read more


Dr. Marsha Davis
425 Doctors shared insights

Drowsiness (Definition)

Drowsiness = feeling sleepy/ feeling ...Read more