{"id":24295,"date":"2021-03-24T09:30:34","date_gmt":"2021-03-24T13:30:34","guid":{"rendered":"https:\/\/www.singlecare.com\/blog\/?p=24295"},"modified":"2025-10-20T11:29:32","modified_gmt":"2025-10-20T15:29:32","slug":"antihistamine-weight-gain","status":"publish","type":"post","link":"https:\/\/www.singlecare.com\/blog\/antihistamine-weight-gain\/","title":{"rendered":"Is your allergy medicine making you gain weight?"},"content":{"rendered":"

Most people are familiar with <\/span>antihistamines<\/span><\/a>, medications that are commonly used to treat allergies. Symptoms can be caused by anything from pollen to dust mites, to feathers or food. Antihistamines are a useful over-the-counter treatment that can help alleviate your allergic reaction.<\/span><\/p>\n

Antihistamines work by blocking histamines, which are the chemicals triggered by your body\u2019s inflammatory responses to an allergen. If your allergy is particularly severe, an <\/span>allergy shot<\/span><\/a> may be used instead. Either way, both courses of treatment help to reduce the side effects of histamines in the body\u2014which could include swelling, sneezing, itching, or hives.<\/span><\/p>\n

However, one of the side effects associated with some antihistamines is weight gain<\/a>, and some patients have even suggested they’ve experienced weight loss after stopping antihistamines. Here’s what you need to know about antihistamine weight gain.<\/span><\/p>\n

Why do antihistamines cause weight gain?<\/span><\/h2>\n

While occasional use of antihistamines to treat allergies is unlikely to affect a person’s weight, studies have found that continued use of some antihistamines might contribute to weight gain and obesity.\u00a0<\/span><\/p>\n

For instance, one <\/span>study<\/span><\/a> conducted by researchers at Yale University “found a relationship between prescription H1 antihistamine use and an increased risk of obesity in U.S. adults over the age of 18.” Meanwhile, a study<\/a><\/span>\u00a0into the effect antihistamines had on Hispanic children found that “many participants may have developed obesity and metabolic syndrome due to this medication\u2019s prolonged intake.”\u00a0<\/span><\/p>\n

“Histamine as a chemical decreases the sense of hunger in part by its direct effect on the brain,\u201d says <\/span>Javeed Siddiqui<\/span><\/a>, MD, MPH, Chief Medical Officer of TeleMed2U’s <\/span>Specialty Clinic<\/span>. \u201cIn contrast, an antihistamine, by way of blocking histamines, would then interfere with this ‘messaging’ to the brain.”\u00a0<\/span><\/p>\n

Dr. Siddiqui continues, “In addition, antihistamines can cause drowsiness, which can lead to decreased activity levels. As such, the impact on weight and antihistamines is likely multifactorial, eating more and decreased activity.”<\/span><\/p>\n

Morgyn Clair, a registered dietitian nutritionist at <\/span>Sprint Kitchen<\/span><\/a> says, “While acute or short term use of antihistamines doesn’t necessarily lead to weight gain, chronic use can cause increased appetite and weight changes. This weight gain is most likely related to the effect that the medications have on histamine. Histamines decrease hunger; when using these medications, hunger can become increased, leading to weight gain over time.”<\/span><\/p>\n

Which antihistamines have been linked to weight gain?<\/span><\/h2>\n

Antihistamine weight gain<\/span><\/a> is a topic that requires more research. However, studies have suggested that some antihistamine medications might cause weight gain more than others.<\/span><\/p>\n

An\u00a0observational obesity study<\/a> found that there appeared to be a correlation between the use of Allegra<\/a> (fexofenadine) and Zyrtec<\/a> (cetirizine) and weight gain.<\/p>\n

Benadryl<\/span><\/a> (diphenhydramine) has also been <\/span>linked to weight gain<\/span> in some patients.<\/span><\/p>\n

However, newer antihistamines such as Claritin (loratadine) are associated with lesser weight gain as compared to the antihistamines mentioned above.\u00a0<\/span><\/p>\n

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Do allergy shots cause weight gain?<\/span><\/h2>\n

Unlike antihistamines, allergy shots and weight gain don’t appear to be linked.\u00a0<\/span><\/p>\n

“We can answer this rather clearly,\u201d Dr. Siddiqui says. \u201cNo, allergy shots are not associated with weight gain. By their very nature, allergy injections are exposing an individual to varying doses of a substance or substances that induce an allergic reaction. Allergy injections, or immunotherapy, are not antihistamines.”\u00a0<\/span><\/p>\n

What happens when you stop taking antihistamines?<\/span><\/h2>\n

Like any medication, it’s important to consult your doctor if you intend to stop taking it. “Antihistamines are medications and should be treated as such,” Dr. Siddiqui advises. “If an individual is taking antihistamines daily, they should discuss with their healthcare provider before stopping. In addition, in some cases it may be more appropriate and safer to taper off antihistamines then abruptly stop taking them.”<\/span><\/p>\n

Maintaining a healthy weight<\/span><\/h3>\n

If you take antihistamines and are concerned about gaining weight, here are some of the ways you can maintain a healthy lifestyle:<\/span><\/p>\n