Can Benadryl make you gain weight?
Sarah Smith
Published Jan 17, 2026
Histamine also acts as a neurotransmitter in our brains playing a key role in wakefulness and preventing sleep, which is why Benadryl (an anti-histamine) makes you sleepy. This effect may actually one of the reasons why anti-histamines can result in weight gain.
Is Benadryl making me fat?
Antihistamines can also make you feel tired and unmotivated to exercise. Antihistamines that can cause weight gain include: Diphenhydramine (Benadryl and others) Cetirizine (Zyrtec)
Do antihistamines make you gain weight?
Studies suggest that the prolonged use of antihistamines like Allegra are linked to a roughly 10% increase in body weight, body mass index, and waist circumference. Children who use antihistamines also appear to be at risk.
Is it okay to take Benadryl every night?
You should not take diphenhydramine every night. While it may be helpful during limited periods of insomnia, your body will build up a tolerance for the medication over time, and it will no longer have the desired effect. After 2 weeks of taking diphenhydramine, you may become dependent on it to fall asleep.
What are the side effects of taking Benadryl every day?
What Are Side Effects of Benadryl?
- drowsiness,
- fatigue,
- tiredness,
- sleepiness,
- dizziness,
- disturbed coordination,
- constipation,
- dry mouth/nose/throat,
Is taking Benadryl long term harmful?
Benadryl is recommended only as a short-term treatment for people with symptoms of allergies or other conditions that the drug treats. If you take Benadryl long term, you may develop long-term side effects of the medication.
What does Benadryl do to your body?
This medication works by blocking a certain natural substance (histamine) that your body makes during an allergic reaction. Its drying effects on such symptoms as watery eyes and runny nose are caused by blocking another natural substance made by your body (acetylcholine).
How many days can you take Benadryl in a row?
Call your doctor if the condition you are treating with diphenhydramine does not improve, or if you have a fever with a headache, cough, or skin rash. Do not use diphenhydramine for longer than 2 weeks to treat sleep problems, or longer than 7 days to treat cold or allergy symptoms.
Can I take Benadryl every day for anxiety?
Benadryl is not intended for long-term use, and while it may reduce anxiety symptoms in some individuals, the risks outweigh the benefits. Although it might provide temporary sleepiness, these effects don't last with regular use.
Will I lose weight if I stop taking antihistamines?
However, one of the side effects associated with some antihistamines is weight gain, and some patients have even suggested they've experienced weight loss after stopping antihistamines.
Which antihistamine is least likely to cause weight gain?
Newer drugs, including cetirizine (Zyrtec), fexofenadine (Allegra) and loratadine (Claritin), are less likely to cause weight gain, according to Long.
Does melatonin cause weight gain?
Melatonin is not associated with weight gain. However, poor sleep is linked with weight gain. According to a study published in the journal JAMA Internal Medicine, not getting enough sleep or having inconsistent sleep patterns is associated with a higher body mass index (BMI).
Can allergies cause weight gain?
Food sensitivities and food allergies do not directly cause your body to pack on extra pounds. However, the symptoms can sometimes have a ripple effect that indirectly leads to weight gain.
What can I take instead of Benadryl?
OTC antihistamines include:
- Brompheniramine (Dimetane)
- Cetirizine (Zyrtec)
- Chlorpheniramine (Chlor-Trimeton)
- Clemastine (Tavist)
- Diphenhydramine (Benadryl)
- Fexofenadine (Allegra)
- Loratadine (Alavert, Claritin)
Can you take Benadryl every day for sleep?
While antihistamines may help you to fall asleep, overall sleep quality is usually not very good, he said. Sometimes, they even have the opposite affect and cause hyperactivity, especially in children. “Using Benadryl or any antihistamine for sleep has no long term benefit,” Alapat said.
How long does Benadryl take to wear off?
For the average healthy adult, elimination half-life ranges from 6.7 to 11.7 hours. So between 6 to 12 hours after taking Benadryl, half the drug will be eliminated from the body. Within two days, the drug will be completely gone from the body.
Can too much Benadryl cause problems?
09-24-2020 FDA Drug Safety Communication
The U.S. Food and Drug Administration (FDA) is warning that taking higher than recommended doses of the common over-the-counter (OTC) allergy medicine diphenhydramine (Benadryl) can lead to serious heart problems, seizures, coma, or even death.
Is Benadryl hard on your liver?
Despite widespread use over many decades, diphenhydramine has not been linked to liver test abnormalities or to clinically apparent liver injury. The reason for its safety may relate its short half-life and limited duration of use. Likelihood score: E (unlikely to be a cause of clinically apparent liver injury).
Does Benadryl cause permanent memory loss?
The research to date has not definitively proven that Benadryl (as a specific individual medication) raises the risk of developing dementia. However, the class of medications Benadryl belongs to (anticholinergics) does appear to be associated with dementia.
Is Benadryl memory loss reversible?
IMPORTANCE. Many medications have anticholinergic effects. The general view is that anticholinergic-induced cognitive impairment is reversible upon medication discontinuation. However, a few studies suggest that anticholinergic medications may be associated with increased dementia risk.
Is Benadryl weight based dosing?
Benadryl dosing is based on weight and not age. The following chart can help determine the correct dose for your child based on your child's weight, but is no substitute for your doctor's advice, and you should always call the pediatrician if you have any questions.
Can you lose weight taking melatonin?
While melatonin alone will not aid in massive weight loss, it is recommended as a complementary weight loss strategy when used with increase in physical activity and a change in poor diet. Weight loss aside, melatonin directly helps regulate insulin sensitivity and acts as an anti-inflammatory.