Understanding Hydroxyzine and Its Uses
Hydroxyzine is a first-generation antihistamine prescribed for several conditions [1.4.1]. It is available under brand names like Atarax and Vistaril, as well as in generic forms [1.5.5]. Its primary uses include:
- Anxiety and Tension: It is used for the short-term management of anxiety and tension caused by nervous and emotional conditions [1.5.1]. It is not considered a first-choice medication for this purpose but can be effective, especially for generalized anxiety disorder [1.5.6].
- Allergic Reactions: Hydroxyzine is effective in relieving itching (pruritus) caused by allergic conditions such as chronic urticaria and atopic or contact dermatoses [1.5.1, 1.5.3].
- Sedation: Due to its sedating effects, it is also used before and after general anesthesia to help produce sleep and control anxiety [1.5.1, 1.5.3].
Hydroxyzine comes in various forms, including tablets, capsules, and an oral syrup or suspension [1.5.1].
How Hydroxyzine Works
The primary mechanism of action for hydroxyzine is blocking the H1 histamine receptor [1.6.1, 1.6.4]. Histamine is a substance in the body that causes allergic symptoms; by blocking its action, hydroxyzine reduces itching and other allergic responses [1.5.3]. Because it can cross the blood-brain barrier, it also causes central nervous system effects like sedation [1.6.1]. For anxiety, it's believed that hydroxyzine may also affect serotonin levels in the brain, a neurotransmitter that plays a role in mood [1.5.6, 1.6.6]. This multifaceted action makes it distinct from many other antihistamines [1.6.1].
Gastrointestinal Side Effects: Does Hydroxyzine Cause Diarrhea?
While effective, hydroxyzine can cause a range of side effects. The most common include drowsiness, dry mouth, and headache [1.4.1, 1.4.6]. Gastrointestinal (GI) side effects are also possible, though some are more common than others.
Constipation is a more frequently reported GI side effect than diarrhea [1.3.6]. This is due to hydroxyzine's anticholinergic properties, which slow the movement of food through the intestines [1.3.6].
However, diarrhea has been reported as a side effect in postmarketing studies and patient experiences [1.2.1, 1.2.4]. Although not considered common, the medication can cause gastrointestinal irritation that results in loose bowel movements [1.2.1]. In some cases, diarrhea can also be a symptom of a rare but serious allergic reaction to hydroxyzine itself [1.2.2, 1.3.6].
Other potential GI side effects include dry mouth, nausea, vomiting, and general abdominal distress [1.3.2, 1.4.1].
Comparison of GI Side Effects: Hydroxyzine vs. Other Antihistamines
First-generation antihistamines often share similar side effect profiles. Here is a comparison of hydroxyzine with other common antihistamines regarding their potential gastrointestinal effects.
| Medication | Common GI Side Effects | Notes |
|---|---|---|
| Hydroxyzine (Vistaril, Atarax) | Dry mouth, constipation, nausea [1.3.2, 1.3.6]. Diarrhea is less common but reported [1.2.4]. | Strong sedative and anticholinergic effects contribute to side effects [1.3.6]. |
| Diphenhydramine (Benadryl) | Dry mouth, constipation, stomach upset [1.8.6]. | Similar side effect profile to hydroxyzine, but hydroxyzine's effects may last longer [1.8.2, 1.8.1]. |
| Cetirizine (Zyrtec) | Generally well-tolerated with fewer GI effects. | A second-generation antihistamine, which is less likely to cause drowsiness and anticholinergic side effects compared to hydroxyzine [1.8.5]. |
| Loratadine (Claritin) | Less likely to cause GI side effects. | Another second-generation antihistamine with a low incidence of sedation and GI issues compared to first-generation options [1.6.3]. |
Managing Hydroxyzine-Induced Diarrhea
If you experience diarrhea while taking hydroxyzine, it is often mild and may resolve on its own as your body adjusts [1.2.1]. However, if it's persistent or severe, here are some steps you can take:
- Stay Hydrated: Diarrhea can lead to dehydration. Drink plenty of water, broths, or drinks with electrolytes to replace lost fluids [1.2.1, 1.7.1].
- Eat Bland Foods: Avoid spicy, greasy, or high-fiber foods that can worsen diarrhea. Opt for the BRAT diet (bananas, rice, applesauce, toast) or other bland foods like potatoes, noodles, and lean poultry [1.2.1, 1.7.4].
- Avoid Other Irritants: Limit caffeine and alcohol, as they can bother your bowels [1.7.2].
- Consider Probiotics: Talk to your healthcare provider about taking probiotic supplements or eating yogurt, which may help restore healthy gut bacteria [1.2.1, 1.7.5].
- Speak with Your Doctor: Do not take any anti-diarrheal medications like loperamide (Imodium) without first consulting your doctor, as they need to rule out an infection [1.7.2]. Combining hydroxyzine with loperamide can also increase side effects like dizziness and drowsiness [1.2.6].
When to See a Doctor
You should contact your healthcare provider if you experience any of the following:
- Diarrhea that is severe, contains blood, or lasts for more than a few days.
- Signs of dehydration, such as decreased urination, extreme thirst, and dizziness [1.7.2].
- Diarrhea accompanied by fever, rash, or other signs of a severe allergic reaction (e.g., swelling of the face, trouble breathing) [1.2.2].
- If any side effects persist or worsen [1.4.3].
Your doctor may adjust your dose or recommend an alternative medication [1.7.5]. It's crucial not to stop taking your medication without professional medical advice.
For more information from an authoritative source, you can visit the National Alliance on Mental Illness (NAMI) page on Hydroxyzine.
Conclusion
To answer the primary question: yes, hydroxyzine can cause diarrhea, but it is not a common side effect. Constipation is reported more frequently due to the drug's anticholinergic effects [1.3.6]. When diarrhea does occur, it's typically due to GI irritation and is often manageable at home [1.2.1]. However, it's important to monitor your symptoms and consult a healthcare professional if the diarrhea is severe, persistent, or accompanied by other concerning signs, as it could indicate a more serious issue like an allergic reaction [1.2.2]. Always communicate openly with your doctor about any side effects you experience to ensure your treatment plan is both safe and effective.
