Taking Benadryl With Tylenol PM
In our latest question and answer, the pharmacist discusses whether or not Tylenol PM can safely be taken with Benadryl.
I take Tylenol PM mostly every night but it doesn't always work. Can I add Benadryl on top of it for better effects?
Aug 01, 2022- Do not take Tylenol PM and Benadryl at the same time because both contain diphenhydramine and taking them together can cause dangerous side effects like excessive drowsiness, dry mouth, and constipation.
- If you need to take both medications, separate the doses by at least four to six hours.
- Avoid driving or operating machinery while using either of these medications since they can cause drowsiness.
Answer
It is not recommended to take Tylenol PM at the same time as Benadryl. Taking these medications together results in duplicate drug therapy of the medication diphenhydramine as both Tylenol PM and Benadryl contain it as an active ingredient. Doses of each should be separated by at least four to six hours.
Tylenol PM
Tylenol PM is a medication that contains:
- Acetaminophen
- Diphenhydramine
The pain reliever component of this medication (acetaminophen) is useful for the treatment of mild to moderate pain. The mechanism of acetaminophen is not fully understood but is believed to inhibit prostaglandins which serve a role in inflammation and pain.
The antihistamine component (diphenhydramine) is useful for aiding in sleep or allergic rhinitis symptoms due to the anticholinergic effect that antihistamines exert on the body. This medication, if used as a sleep aid, is recommended to be taken about one hour before the desired hour of sleep.
Each dose (e.g. tablet, capsule) of Tylenol PM contains 500 mg of acetaminophen and 25 mg of diphenhydramine.
Benadryl
Unlike Tylenol PM, Benadryl only contains diphenhydramine which is a 1st generation antihistamine. First-generation antihistamines are known for their sedative effects and relatively short duration of action. The common uses of this medication are for allergy relief, insomnia, and the prevention or treatment of motion sickness. The same anticholinergic, sedating and drowsy side effects are expected with this medication as with Tylenol PM.
Each dose of Benadryl (e.g. tablet, capsule) contains 25 mg of diphenhydramine.
Taking Benadryl With Tylenol PM
The use of these medications together will result in an additive effect of toxicities and not in therapeutic benefit as both medications contain diphenhydramine in the active ingredients. Effects which may be intensified include:
- Sedation
- Drowsiness
- Dry mouth
- Dry eyes
- Constipation
When taking either of these medications, it is recommended to take them at night time due to the potential to induce sleep. The use of heavy machinery or operating vehicles is also not recommended while using either of these medications.
Lastly, it is important to note that some sources indicate the dosage of Benadryl for the treatment of insomnia to be 50 mg, or two tablets. Therefore, if necessary, you can safely take one Benadryl tablet with Tylenol PM to equal a dose of 50 mg of diphenhydramine, but this would be the maximum dose. This also isn't generally recommended due to the risk of overdosing using multiple medications. Final Words
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Glossary — Terms in This Answer
- Diphenhydramine
- An active ingredient found in both Tylenol PM and Benadryl that helps relieve allergies and aids sleep.
- Acetaminophen
- A pain reliever and fever reducer that is the active pain-relief ingredient in Tylenol PM.
- Antihistamine
- A type of medication that blocks the body's histamine response to reduce allergy symptoms and promote sleep.
- Prostaglandins
- Chemicals in the body that play a role in inflammation and pain, which acetaminophen works to inhibit.
- Anticholinergic effect
- A side effect of antihistamines that causes drowsiness, dry mouth, and dry eyes by affecting nerve signals in the body.
- Allergic rhinitis
- Allergy symptoms affecting the nose, such as sneezing and nasal congestion.
- Duplicate drug therapy
- Taking two medications that contain the same active ingredient, which can lead to overdose and dangerous side effects.
- First-generation antihistamine
- An older class of antihistamine medication known for causing drowsiness as a side effect.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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