Antihistamines vs. Corticosteroids: What’s the Difference?

Antihistamines and corticosteroids are both medications used to treat allergies. In this way, they both work on the immune system. Antihistamines are typically used to treat common allergies. They work by reducing the impact of histamine production in the body.

Histamine is a naturally occurring chemical associated with immune system functioning. Corticosteroids are strong anti-inflammatory medications that work to reduce inflammatory processes in the body and reduce overactive immune system activity.  

In this article, you’ll learn about antihistamine types, corticosteroid types, the difference between antihistamines and corticosteroids, side effects to consider, and potential drug interactions.

Woman looking at drugs in pharmacy

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What Are Antihistamines?

Antihistamines are a class of drugs that block the effects of histamine in the body. There are two types of antihistamines. The type of antihistamine needed will depend on the reaction or condition being treated. 


H1 blockers are a type of antihistamine used to treat allergies. This class of antihistamine also treats:

  • Common cold symptoms
  • Short-term insomnia
  • Anxiety


First-generation antihistamine overdose causes toxicity and can be fatal.

The second type of antihistamine is known as H2 blockers or H2 receptor antagonists.H2-blockers are used to treat gastrointestinal conditions. H2-blockers may be used in the treatment of the following conditions or symptoms:

Examples of common H2 blockers include:

What Are Corticosteroids?

Corticosteroids are steroid medications used to treat overactive immune system activity.



Glucocorticoids are a synthetic version of the naturally occurring glucocorticoid hormone present in the body. They help prevent cell tissue and organ damage caused by excessive inflammation by reducing immune system activity.

Glucocorticosteroid Uses

Glucocorticosteroids are used in the treatment chronic inflammatory health conditions such as:

  • Rheumatoid arthritis
  • Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis
  • Lupus
  • Vasculitis (blood vessel inflammation)
  • Asthma
  • Chronic obstructive pulmonary disease (COPD)

Examples of glucocorticoids include:

  • Prednisone
  • Prelone (Prednisolone)
  • Medrol (Methylprednisolone)
  • Kenalog (Triamcinolone)


Mineralocorticoids are a class of drugs designed to help regulate water and salt in the body. They work on the adrenal cortex part of the adrenal gland. Mineralocorticoids are used in the treatment of adrenal fatigue and kidney disease.

What’s the Difference Between Antihistamines and Corticosteroids?

Both medications work to reduce immune system activity. The difference between antihistamines and corticosteroids are the chemical processes they are targeting. Antihistamines target histamines to reduce their impact on the immune system and inflammatory processes. Corticosteroids work by reducing upstream chemical reactions causing inflammation.

Side Effects

The following are the side effects of antihistamines and corticosteroids.

Antihistamines Side Effects

Side effects associated with antihistamine use will vary depending on whether you’re taking first- or second-generation antihistamines. Side effects will also vary depending on whether you’re taking H1 or H2 blockers. Side effects of nasal antihistamines include sneezing and upper respiratory infection.

First-generation histamines have the following common side effects:

  • Drowsiness or excessive fatigue 
  • Dry mouth and eyes
  • Vision problems 
  • Low blood pressure
  • Mucus thickening in airways making it more difficult to breathe 
  • Rapid heart rate 
  • Troubles with urinating or passing bowel movements (i.e., constipation)

While side effects can occur, one review of medical literature found most second-generation antihistamines are well-tolerated and serious side effects are rare.

Side effects associated with second-generation antihistamines include:

  • Headache
  • Cough and sore throat
  • Tiredness 
  • Abdominal pain or discomfort
  • Nausea and vomiting

Side effects of H2 blocker antihistamines tend to be rare but may include:

Corticosteroid Side Effects

Short-term side effects of taking corticosteroids include:

Experts say the anti-inflammatory properties of glucocorticoids are useful for short-term use in most cases, but chronic and systemic use usually causes side effects, and results in reducing sensitivity to the medication.

Long-term or high-dose side effects from corticosteroids can include a series of side effects leading to other health complications, including:

  • Osteoporosis or severe bone density loss 
  • Insulin resistance
  • Hypertension
  • Muscle weakness or atrophy
  • Severe infection due to reduce immune system activity
  • Symptoms of Cushing's syndrome
  • Peptic ulcers
  • Neuropsychiatric disorders

Drug Interactions

The following are drug interactions to be aware of when taking antihistamines and corticosteroids. Speak with a healthcare provider before starting any new medication.


Antihistamines interact with other medications and substances, causing drowsiness or excessive fatigue.

This includes over-the-counter and prescription-strength medications such as:

  • Sleep medications and other sedatives
  • Pain medications
  • Muscle relaxants
  • Antidepressants
  • Anti-seizure medications

Antihistamines can also interact with antipsychotics and some drugs to prevent vomiting, such as Compro (prochlorperazine) and Promethazine DM (promethazine and dextromethorphan).


Corticosteroids may interact with medications, impacting the digestive system and metabolism. These include Nizoral (ketoconazole) and Norvir or Kaletra (ritonavir). 

If you’re unsure if a medication interacts with antihistamines or corticosteroids, you can ask a pharmacist to review your medication list.


Consuming more than one type of antihistamine at a time without directions from a medical provider is not safe. Antihistamine overdose can cause seizures, hallucinations, and heart attacks, and can be fatal. Moreover, antihistamines and corticosteroids may contain additional medicinal ingredients such as decongestants. Taking more than one type of decongestant increases your risk of overdose. Always check the labels of new and old medications to prevent doubling up on dosage.


Antihistamines and corticosteroids work to reduce immune system activity. Antihistamines block histamine action that occurs from allergies. Corticosteroids work on additional chemicals involved in the immune system and inflammatory processes. Types of antihistamines include first and second-generation and nasal antihistamines. Types of corticosteroids include synthetic corticosteroids and mineralocorticoids.

Side effects of antihistamines depend on type, with second-generation antihistamines having fewer side effects than first-generation drugs. Corticosteroid side effects include fluid retention and weight gain. Antihistamines interact with other medications causing drowsiness, antipsychotics, and some anti-vomiting medications. Corticosteroids interact with drugs affecting metabolism. If you have questions about a certain medication interacting with an antihistamine or corticosteroid, consult a pharmacist.

Frequently Asked Questions

  • Are antihistamines and corticosteroids the same?

    No. Antihistamines and corticosteroids are not the same. Antihistamines are medications that reduce histamine activity related to allergies. Corticosteroids are medications that reduce immune system activity associated with chronic conditions causing chronic inflammation.

  • Is it OK to take antihistamines and corticosteroids at the same time?

    It’s generally OK to take antihistamines and corticosteroids at the same time, depending on your symptoms and if your healthcare provider advises it. However, taking more than one antihistamine at a time can lead to dangerous health complications unless under the careful direction of a medical provider. 

  • Are antihistamines and corticosteroids safe during pregnancy?

    Some antihistamines and/or corticosteroids are recommended to treat certain conditions during pregnancy. It is important to ask your healthcare provider before using any medication during pregnancy.

  • Are nasal steroids better than antihistamines for nasal allergy?

    Yes. Research suggests nasal steroids are better than antihistamines for reducing symptoms of nasal allergy or allergic rhinitis. Nasal steroids performed better in improving sleep, daytime sleepiness, sneezing, itchiness, and congestion. This suggests nasal steroids can be the first option for treating nasal allergy.

  • Do antihistamines help reduce inflammation?

    Yes, antihistamines help reduce inflammation. Antihistamines reduce inflammation by blocking histamine receptors associated with inflammatory immune system responses. Research also suggests they work to reduce inflammation by suppressing different pathways associated with inflammation.

  • Which medicine is best for allergies?

    The medicine that is best for allergies will depend on the cause of the allergic reaction. However, generally speaking, second- generation antihistamines and nasal steroids are best for allergies. Consult with your healthcare provider or pharmacist for additional information specific to your health needs. 

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Michelle Pugle
Michelle Pugle, BA, MA, is an expert health writer with nearly a decade of contributing accurate and accessible health news and information to authority websites and print magazines. Her work focuses on lifestyle management, chronic illness, and mental health. Michelle is the author of Ana, Mia & Me: A Memoir From an Anorexic Teen Mind.