The short answer
Benadryl is an Over-The-Counter (OTC) medicine that contains diphenhydramine. It is an antihistaminic agent used to relieve symptoms of allergic reactions. Moreover, Benadryl is found to help with nausea by blocking the signaling to the chemoreceptor trigger zone in your brain which is responsible for controlling nausea and vomiting.
- Benadryl is an antihistaminic agent that contains diphenhydramine HCl which is used to relieve symptoms of allergic reactions.
- Besides its action against allergy, Benadryl is found to help with nausea and vomiting.
- Benadryl can be used to prevent and treat nausea during pregnancy. However, a high dose of diphenhydramine is found to have oxytocin-like effects. Therefore, high doses of diphenhydramine should be avoided during pregnancy.
- Diphenhydramine acts by blocking the signaling to the chemoreceptor trigger zone in your brain which is responsible for nausea sensation and vomiting.
What is Benadryl used for?
BENADRYL® is an antihistaminic medicine that contains diphenhydramine HCl. This antihistaminic agent is used to relieve symptoms associated with the common cold, allergy, and upper respiratory allergy.
Histamine is an inflammatory mediator that is released when your body fights against invading foreign body. Histamine release commonly results in symptoms such as sneezing, runny nose, and watery eyes. Benadryl as an antihistamine medicine can block the action of histamine and, therefore, help with allergic symptoms.
Benadryl is used for the following:
- Allergic reactions
- Sleep disturbance
- Motion sickness
- Common cold
- Parkinsonism (mild cases)
Does Benadryl help with nausea?
The answer is yes. Benadryl can help with nausea.
Benadryl is an OTC medicine that contains an antihistaminic agent (diphenhydramine HCl) However, it is found to help with nausea and vomiting especially those related to motion sickness.
Diphenhydramine HCl is a first-generation antihistaminic agent that is found to have several indications that primarily include nausea and vomiting associated with motion sickness and vertigo. Also, its secondary indications are to treat allergic rhinitis, insomnia, allergic reactions, and parkinsonism.
A previous study investigated the efficacy of diphenhydramine in reducing vertigo and nausea induced by the ultra-high static magnetic field at 7 T. Results showed that diphenhydramine, even at a low dose, was able to reduce nausea and vertigo induced by ultra-high static magnetic fields. Therefore, it can be used as a prophylaxis therapy to avoid nausea and vertigo.
Does Benadryl help with nausea during pregnancy?
The answer is yes. Benadryl can be safely used to treat nausea during pregnancy.
It is reported that more than half of pregnant women suffer from nausea and vomiting. Nausea and vomiting among pregnant women begin by the 4th week and disappear by the 16th week of pregnancy. The main causes of nausea and vomiting in pregnancy are unknown. However, it may be attributed to the rise in human chorionic gonadotrophin concentration (Ref).
The safety data showed that Benadryl (Diphenhydramine) is safe with pregnancy and can be considered a non-teratogenic compound. Therefore, it can be used during pregnancy for the treatment of nausea and vomiting and also for the treatment of allergic symptoms such as rhinitis and pruritus (Ref).
However, diphenhydramine is classified as class B and it shows oxytocin-like effects, especially in high dosages (Ref). Moreover, adverse reactions that do not occur in nonpregnant patients may occur in pregnant patients. A study showed that a combination of diphenhydramine and temazepam can a significant increase in fetal morbidity.
Therefore, diphenhydramine should be used with caution during pregnancy.
How Benadryl can help with nausea?
Benadryl contains diphenhydramine HCl classified as an antihistaminic agent and acts by blocking H1 receptors.
H1 receptors are located in the Central Nervous System (CNS) area which also includes the area postrema (the area postrema has been implicated as a chemoreceptor trigger zone for vomiting) and vomiting center in the vestibular nucleus.
The antihistamines such as diphenhydramine can block messages to the part of the brain that controls nausea and vomiting thus reducing the nausea sensation.
The lipophilic property is essential for its activity as it should be able to cross the blood-brain barrier (BBB) to affect the central nervous system and thus produce its effect.
How quickly does Benadryl work for nausea?
Benadryl can help with nausea by blocking the H1 receptor and preventing signaling to the chemoreceptor trigger zone in your brain. Therefore, it may take time to be absorbed and reach its site of action.
Accordingly, it may need 1-2 hours to give its action. So, it is better to take Benadryl as a prophylaxis against nausea in motion sickness or other cases of nausea and take into consideration that it may work 1 to 2 hours after its administration.
What are the common side effects of Benadryl?
As an antihistaminic medicine, Benadryl is associated with side effects including the following:
- Dry mouth
- Blurred vision
- Higher risk of fall
1. When should you take Benadryl?
You should follow the directions on the product package or follow your doctor’s instructions. You can ask the pharmacist in case you use it without a prescription. BENADRYL is an over-the-counter (OTC) allergy medication.
It is usually taken every 4-6 hours to relieve symptoms of allergic reactions. Typically, Benadryl with a dose range of 25 to 50 mg can be administered orally every 6 hours, or as needed (Ref).
2. Should I drink water after taking Benadryl?
The answer is Yes. You should drink a glass of water after each dose of Benadryl.
Dry mouth is one of the common side effects of Benadryl. Therefore, drinking water can help with dry mouth results from Benadryl.
3. Does Benadryl help with sleep?
The answer is yes. Benadryl can help with sleeping
Diphenhydramine is a first-generation antihistaminic that is characterized by a lipophilic nature and can penetrate the blood-brain barriers (BBB) leading to sleeping as a common side effect.
It may take 1 hour to act. So, you should take it 1 hour before bedtime if you take it to help you with sleep.
4. Does Benadryl cross the placenta?
The answer is yes.
Benadryl contains Diphenhydramine which is a lipophilic compound that is reported to cross the placenta (Ref).