Does fexofenadine interact with trazodone? (3+ side effects)

In this article, we will discuss whether fexofenadine and trazodone can interact with each other or not. We will further explore the possible interactions between them, what research suggests on this, the potential risks and side effects and some safety precautions and recommendations.

Does fexofenadine interact with trazodone?

Yes, fexofenadine and trazodone may interact with each other. Both of these medications have sedative effects and their concomitant use might enhance the sedation. However, fexofenadine belongs to second-generation antihistamines which are less likely to cause sedation compared to the first generation of antihistamines. (1,2)

Trazodone, an antidepressant, is FDA-approved for the treatment of major depressive disorder. It belongs to a class of SARIs (serotonin antagonist reuptake inhibitors). It exerts its effects by increasing the levels of serotonin in the brain, which is an important neurotransmitter that alters your mood and boosts motivation. It may also be used off-label to promote sleeping quality in insomniac people. (1)

Fexofenadine, on the other hand, is an antihistamine (anti-allergic) medication. It works by blocking H1 receptors and is widely used to reduce the symptoms of allergic conditions like hay fever or allergic rhinitis, hives, sneezing, runny nose, itching, watery eyes etc. (2)

It’s very important to keep in mind that everyone is different and may react differently to medications because their brain chemistry varies. If you have any concerns about taking fexofenadine and trazodone together, it’s crucial to discuss this with your healthcare provider. 

What are the possible interactions between fexofenadine and trazodone?

Fexofenadine (an antihistamine) and trazodone (an antidepressant) are generally considered safe when taken together and there are not many documented interactions between the two. They both have distinct mechanisms of action and different intended purposes of use. (4)

However, both fexofenadine and trazodone have one similar effect which is sedation. Trazodone is associated with more pronounced sedation and taken in combination with fexofenadine may have an enhanced additive effect on drowsiness. Their combined effect can cause disruptions in activities that require alertness and focus. (3,4)

Trazodone can cause depression in the central nervous system. While fexofenadine is not much sedating, it may have the potential for increased CNS depression when taken with trazodone, particularly at higher doses of trazodone. (1)

Fexofenadine is designed to have fewer anticholinergic side effects being a second-generation antihistamine as it has minimal potency to penetrate the central nervous system, however, trazodone may have some anticholinergic properties and combining it with fexofenadine can potentially exacerbate these effects. Certain anticholinergic side effects may include, dry mouth, blurred vision, constipation, increased heart rate etc. (2)

What does research suggest?

According to a research study, scientists performed a clinical evaluation on 12 patients (9 male and 3 women) to determine the effects of antidepressants affecting serotonin levels in people taking fexofenadine for allergic purposes. They gave an initial 60mg dose of fexofenadine to each individual, then they were given antidepressants for 7 days. After this, they gave another fexofenadine shot to every individual of 60mg. (3)

The researchers found out that certain antidepressants like trazodone increase the amount of fexofenadine in the blood. Therefore, this study shows that antidepressants can impact the way fexofenadine is processed by the body and also affects its metabolism in the liver and the rate of elimination from the body is also increased. (3)

It’s important to consult a healthcare professional before taking these medications together so that they might assess your specific condition and tailor a treatment plan accordingly. 

What are the potential ADRs of taking fexofenadine and trazodone together?

It’s essential to be aware of certain possible side effects related to trazodone and fexofenadine concomitant use, some of which may include: (1,2)

• Drowsiness and sedation
• Impaired cognitive function (affecting memory and concentration)
• Dry mouth
• Blurred vision 
• GIT discomfort (might include nausea, diarrhoea or constipation)
• Urinary retention
• Increased heart rate (increased risk of tachycardia)
• Allergic reactions (Some individuals may be allergic to fexofenadine or trazodone leading to symptoms like rash, itching and swelling on the skin)
• Serotonin syndrome (This condition is usually associated with higher doses of trazodone and symptoms might include fever, changes in blood pressure, seizures, muscle rigidity, hallucinations, confusion etc)

What factors increase the risk of side effects from this combination?

Certain individuals might be more sensitive and at increased risk of experiencing side effects from the trazodone and fexofenadine combination. Factors increasing the risk of side effects may include: (4)

Age: 

Older people might be at increased risk of sedative effects from trazodone and fexofenadine, mostly because of their age-related changes in metabolism and reduced drug clearance can also influence how these medications are processed in the body. 

Liver or kidney impairment:

Individuals having any renal or liver conditions that might have affected their intended functions might be at greater risk of experiencing side effects due to the alterations in metabolism and elimination process of medications by these organs. 

Existing health conditions: 

People with pre-existing health conditions, specifically those affecting the heart, liver, kidneys or central nervous system may be more vulnerable to the side effects of these medications. Cardiac arrhythmias and QT-interval prolongation can exacerbate the serious side effects associated with trazodone. 

Alcohol consumption: 

Drinking too much alcohol can enhance the sedative effects of trazodone and fexofenadine and may increase the risk of drowsiness and impaired coordination. 

Genetic factors: 

The genetic makeup of an individual significantly influences how they metabolize and respond to certain medications. Variations in genes that are involved in drug metabolism may affect the risk of side effects. 

History of allergies: 

People who already have some history of allergies related to antihistamines or antidepressant use are more likely to experience exacerbated side effects from this combination. 

Individual sensitivity: 

Everyone’s body may react differently to medications. Some individuals may be more sensitive to the sedative effects of these drugs while others might tolerate them well with not much bothersome side effects.

What to do if you experience fexofenadine-trazodone-induced side effects?

If you experience any of the aforementioned side effects from the trazodone-fexofenadine combination, it’s crucial to reach out to your healthcare provider. Communicate the nature and severity of your symptoms and all the relevant details accurately. (1)

Follow the advice and instructions provided by your doctor. They may adjust your dosage and increase the time between both medications that are to be taken which helps limit the interaction of two drugs. Do not alter the dose or switch to some other alternative on your own and never stop taking the medication (trazodone) abruptly, as this will cause you to deal with consequential withdrawal side effects. (1,2)

Avoid overconsumption of alcohol and quit smoking. Don’t use any substance that may exacerbate the effects of drowsiness. If you’re experiencing a lot of dry mouth, drinking plenty of water and keeping yourself hydrated might help alleviate this symptom. (3,4)

If excessive drowsiness or impaired cognitive functions is a concern, try not engaging yourself in activities that require focus and concentration like driving or operating heavy machinery to avoid any mishap. 

As a pharmacist, I’d advise you to not take any OTC medication or herbal supplement to treat any subsidiary condition without consulting and informing your doctor. They may evaluate the risk-to-benefit ratio profile based on your specific condition and recommend the treatment plan for the best possible outcome.

Always stick to the prescribed instructions and guidelines given by your doctor in terms of dose, timing of medications, dietary intake, substances to avoid and healthy lifestyle modifications like exercise. 

References