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Drug Info

Does hydroxyzine affect your weight?

This antihistamine may indirectly cause weight loss or weight gain
T. Duncan
By | May 30, 2024 Medically reviewed by Karen Berger, Pharm.D.
Pills and a scale | Hydroxyzine weight loss

Key takeaways

  • Hydroxyzine is an antihistamine used to treat allergies, allergic reactions, and anxiety disorders.

  • Its side effects, such as increased appetite or sedation, may indirectly cause weight gain. Treating anxiety could cause weight loss for people who stress eat.

  • There is no significant clinical evidence linking hydroxyzine to weight loss or weight gain.

In this article:

Hydroxyzine is an antihistamine that is used to treat allergies, allergic reactions, and anxiety disorders. Side effects are a common concern when starting a new medication, especially if it’s one you need every day to avoid allergy symptoms or manage your mental health. After all, weight gain is a known possible side effect of antihistamines and most antidepressants. If you’re prescribed hydroxyzine, also known by brand names like Atarax and Vistaril, you may be wondering: Will this medication make you gain weight? The short answer is no; it’s not a direct side effect of taking hydroxyzine. However, it’s possible this drug can affect your waistline. 

How does hydroxyzine impact your weight?

Hydroxyzine works by stopping the effects of histamine in your body—specifically, by blocking the H1 receptor in your central nervous system. This prevents allergy symptoms like sneezing, itchy eyes, runny nose, and cough. It also reduces anxiety, promoting feelings of calm and relaxation. These two effects—blocking histamine and mild sedation—can impact your appetite and activity level, which could indirectly affect your waistline.

Does hydroxyzine cause weight gain?

Antihistamines like hydroxyzine may increase your appetite. Additionally, sedation and sleepiness are two of the main side effects of hydroxyzine. “Endocrinologically, hydroxyzine could affect weight by influencing neurotransmitter pathways involved in appetite regulation,” says Linda Khoshaba, NMD, a naturopathic endocrinologist in Scottsdale, Arizona. Hydroxyzine could alter hormonal signaling related to metabolism or modulate stress hormones like cortisol, which can impact both appetite and metabolic function, says Khoshaba.

These combined effects could lead to changes in dietary habits and physical activity levels, indirectly impacting your weight. In other words, if the medication makes you eat more and move less, you may gain a few pounds.

“In clinical practice, weight changes in patients taking hydroxyzine have yielded mixed results. Some patients may gain weight as a result of increased appetite or reduced activity levels caused by the medication’s sedative effects,” says Paul Daidone, MD, a healthcare provider based in Fayetteville, Arkansas, and Medical Director at True Self Recovery. However, not all patients taking hydroxyzine experience significant weight gain. There may be individual factors at play, such as mental health, other medical conditions, lifestyle, and concurrent medications—both over-the-counter (OTC) and prescription—that are affecting weight rather than the antihistamine.

Does hydroxyzine cause weight loss?

No, hydroxyzine does not directly cause weight loss. However, its role in managing anxiety disorders could indirectly affect eating patterns, potentially supporting weight management. For example, some people eat more—or eat less healthy food—also known as stress eating—when they’re dealing with anxiety. Hydroxyzine may help curb stress-induced unhealthy eating by tempering anxiety. However, hydroxyzine should not be considered a weight-loss medication and should not be prescribed for that purpose.

Hydroxyzine and weight management

Hydroxyzine’s efficacy for weight management is unknown. Its ability to reduce anxiety may have indirect benefits for weight control, particularly in reducing stress-eating behaviors. “Chronic stress and inflammation are associated with changes in appetite, metabolism, and weight regulation. By alleviating these conditions, hydroxyzine may contribute to weight stability or even weight loss in some individuals,” explains Khoshaba. Its antihistamine properties may increase the appetite of those who need to gain weight. However, while hydroxyzine has a potential role in weight management, conclusive clinical evidence is required in order to support its use.

In other words, hydroxyzine should not be considered a primary tool for achieving weight gain or loss. If you are taking this prescription drug for allergies or anxiety and notice you are gaining or losing a few pounds, seek medical advice about this side effect from your prescribing healthcare provider.

Patients taking hydroxyzine on a routine basis should be monitored for significant weight changes or any signs that hydroxyzine use may be causing behavioral changes that could lead to weight gain or loss. “This includes regular weigh-ins and discussions about diet, exercise, and overall health,” says Daidone. “Paying attention to patients’ reports of increased appetite or changes in physical activity levels can be early indicators of potential weight impact.”

Potential side effects of hydroxyzine for weight loss

The side effects of hydroxyzine may impact weight management efforts. No matter the reason you’re prescribed this medication, common side effects of hydroxyzine include:

  • Dry mouth
  • Changes in appetite
  • Drowsiness
  • Dizziness
  • Constipation (especially in older adults)
  • Confusion (especially in older adults)
  • Headache

Rare but more serious adverse effects include:

  • Abnormal heart rhythm
  • Unintentional trembling or shaking
  • Seizures

These serious side effects can be signs of a health condition called long QT syndrome. Heart rhythm problems such as this can be life-threatening when untreated. If you notice any of these symptoms, contact a healthcare professional immediately. 

Additionally, individuals with metabolic conditions should be careful using hydroxyzine. “Antihistamines can sometimes affect blood sugar levels and thyroid function,” says Khoshaba. Thus, close monitoring and potential adjustments to medication regimens may be necessary for these patients.

You should always tell your healthcare provider or pharmacist about all over-the-counter and prescription medications you are taking, including vitamins or supplements, before starting a new medication to avoid drug interactions. Particularly with hydroxyzine, you should mention other antihistamines, anxiety medications, antidepressants, heart medications, seizure medications, and other medications that can cause drowsiness—like sedatives, sleeping pills, or tranquilizers.

The bottom line: Hydroxyzine side effects may affect weight

Hydroxyzine may have indirect effects on weight because of side effects, including sedation and increased appetite. It can also cause changes in eating patterns due to reduced anxiety. This medication should not be seen as a primary treatment option for weight management—but rather as a drug with possible side effects impacting weight.