Allegra and Olanzapine drug interactions - a phase IV clinical study of FDA data


Drug interactions are reported among 61 people who take Allegra and Olanzapine. Common interactions include haematochezia among females, and altered state of consciousness among males.

The phase IV clinical study analyzes what interactions people who take Allegra and Olanzapine have. It is created by eHealthMe based on reports from the FDA, and is updated regularly. You may use the study as a second opinion to make health care decisions.

Phase IV trials are used to detect adverse drug outcomes and monitor drug effectiveness in the real world. With medical big data and AI algorithms, eHealthMe is running millions of phase IV trials and makes the results available to the public. Our original studies have been referenced on 700+ medical publications including The Lancet, Mayo Clinic Proceedings, and Nature.

On Sep, 28, 2023

61 people who take Allegra and Olanzapine together, and have interactions are studied.

What is Allegra?

Allegra has active ingredients of fexofenadine hydrochloride. It is used in allergies. Currently, eHealthMe is studying from 72,432 Allegra users.

What is Olanzapine?

Olanzapine has active ingredients of olanzapine. It is used in bipolar disorder. Currently, eHealthMe is studying from 63,439 Olanzapine users.

Number of Allegra and Olanzapine reports submitted per year:

Allegra and Olanzapine drug interactions.

Common Allegra and Olanzapine drug interactions by gender *:


  1. Haematochezia
  2. Hallucination, auditory
  3. Heat stroke
  4. Headache
  5. Asthenia
  6. Device failure
  7. Drug toxicity
  8. Fatigue
  9. Suicidal ideation
  10. Vision blurred


  1. Altered state of consciousness
  2. Transient ischaemic attack
  3. Rash
  4. Skin fissures
  5. Tardive dyskinesia
  6. Acne pustular
  7. Diabetes mellitus
  8. Drug ineffective
  9. Drug resistance
  10. Obesity

Common Allegra and Olanzapine drug interactions by age *:






  1. Bronchopulmonary aspergillosis allergic
  2. Deep vein thrombosis
  3. Fatigue
  4. Headache
  5. Infective pulmonary exacerbation of cystic fibrosis
  6. Somnolence
  7. Acne pustular
  8. Depressed level of consciousness
  9. Drug ineffective
  10. Drug resistance


  1. Anaemia
  2. Hospitalisation
  3. Hypothyroidism
  4. Pancreatitis acute
  5. Somnolence
  6. Suicidal ideation
  7. Surgery
  8. Apnoea
  9. Asthenia
  10. Chest pain


  1. Blindness transient
  2. Crying
  3. Diabetes mellitus
  4. Vision blurred
  5. Vomiting
  6. Abortion spontaneous
  7. Alanine aminotransferase increased
  8. Aspartate aminotransferase increased
  9. Blindness hysterical
  10. Blood alkaline phosphatase increased


  1. Device failure
  2. Drug toxicity
  3. Headache
  4. Sleep apnoea syndrome
  5. Surgery
  6. Administration site reaction
  7. Back pain
  8. Cystitis
  9. Diabetic coma
  10. Erythema


  1. Rhabdomyolysis
  2. Cellulitis
  3. Delusion
  4. Hyperlipidaemia
  5. Hypertension
  6. Oedema
  7. Paraesthesia


  1. Asthenia
  2. Balance disorder
  3. Arthritis infective
  4. Arthropathy
  5. Blood potassium decreased
  6. Cardiac failure
  7. Decreased appetite
  8. Dehydration
  9. Diarrhoea
  10. Dysgeusia

Common conditions people have *:

  1. Narcolepsy (brain's inability to regulate sleep-wake cycles normally): 17 people, 27.87%
  2. Cataplexy (loss of muscle tone accompanied by full conscious awareness): 9 people, 14.75%
  3. Pain: 8 people, 13.11%
  4. Nausea (feeling of having an urge to vomit): 4 people, 6.56%
  5. Chronic Inflammatory Demyelinating Polyradiculoneuropathy (long lasting infection of nerves outside brain and spinal cord): 4 people, 6.56%

* Approximation only. Some reports may have incomplete information.

Do you take Allegra and Olanzapine?

Personalize this study to your gender and age

How to use the study?

You can discuss the study with your doctor, to ensure that all drug risks and benefits are fully discussed and understood.

Related publications that referenced our studies

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Drug side effects by duration, gender and age:

Common Allegra drug interactions:

Browse interactions between Allegra and drugs from A to Z:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Common Olanzapine drug interactions:

Browse interactions between Olanzapine and drugs from A to Z:

a b c d e f g h i j k l m n o p q r s t u v w x y z

How the study uses the data?

The study uses data from the FDA. It is based on fexofenadine hydrochloride and olanzapine (the active ingredients of Allegra and Olanzapine, respectively), and Allegra and Olanzapine (the brand names). Other drugs that have the same active ingredients (e.g. generic drugs) are not considered. Dosage of drugs is not considered in the study. Patients in the study may take other drugs besides Allegra and Olanzapine.

Who is eHealthMe?

With medical big data and proven AI algorithms, eHealthMe provides a platform for everyone to run phase IV clinical trials. We study millions of patients and 5,000 more each day. Results of our real-world drug study have been referenced on 700+ medical publications, including The Lancet, Mayo Clinic Proceedings, and Nature. Our analysis results are available to researchers, health care professionals, patients (testimonials), and software developers (open API).


WARNING: Please DO NOT STOP MEDICATIONS without first consulting a physician since doing so could be hazardous to your health.

DISCLAIMER: All material available on is for informational purposes only, and is not a substitute for medical advice, diagnosis, or treatment provided by a qualified healthcare provider. All information is observation-only. Our phase IV clinical studies alone cannot establish cause-effect relationship. Different individuals may respond to medication in different ways. Every effort has been made to ensure that all information is accurate, up-to-date, and complete, but no guarantee is made to that effect. The use of the eHealthMe site and its content is at your own risk.

If you use this eHealthMe study on publication, please acknowledge it with a citation: study title, URL, accessed date.

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