What Sets Antihistamines Apart From Corticosteroids?

What Sets Antihistamines Apart From CorticosteroidsWith spring approaching, many of us will rely on allergy medications such as antihistamines and corticosteroids. While both drugs are used to treat allergies and affect the immune system, they work in different ways. Antihistamines are commonly used for treating allergies and work by decreasing the impact of histamine production. Histamine is a naturally occurring chemical that is associated with immune system function. In contrast, corticosteroids are powerful anti-inflammatory medications that work to reduce inflammation and dampen an overactive immune system.

This article will provide information on the various types of antihistamines and corticosteroids, outline the differences between these medications, discuss potential side effects and drug interactions, and help you make informed decisions about which medication to choose.

Define Antihistamines?

Antihistamines are medications that can inhibit the effects of histamine within the body. There are two distinct types available, and the specific type used will vary depending on the particular reaction or medical condition that is being treated.


H1 blockers are a specific type of antihistamine medication that is commonly utilized for treating allergy symptoms. This class of antihistamine also treats:2

Overdosing on first-generation antihistamines can lead to toxicity, which can even result in fatality. On the other hand, the second type of antihistamine is referred to as H2 blockers or H2 receptor antagonists. These are commonly employed for the management of gastrointestinal disorders. H2 blockers may be prescribed for addressing symptoms or conditions such as

  • Chronic acid reflux and heartburn, or gastroesophageal reflux disease (GERD)
  • Peptic ulcers
  • Gastritis
  • Nausea
  • Vomiting
  • Motion sickness
  • Zollinger-Ellison syndrome (tumors grow in the pancreas or duodenum, the upper part of the small intestine)

 Examples of common H2 blockers include:

  • Axid (Nizatidine)
  • Pepcid (Famotidine)
  • Zantac (Ranitidine)

What Are Corticosteroids?

Corticosteroids, it’s a type of steroid medication, are employed for managing overactive immune system reactions.



Glucocorticoids are an artificial form of the naturally occurring glucocorticoid hormone that is found within the body. By reducing immune system activity, they assist in preventing cell, tissue, and organ damage induced by excessive inflammation.

Glucocorticosteroid Uses

Glucocorticosteroids are employed in the management of chronic inflammatory medical 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 group of medications intended to assist in regulating the balance of salt and water in the body. They operate on the adrenal cortex component of the adrenal gland. These drugs are utilized for managing conditions such as adrenal fatigue and kidney disease.

What’s the Difference Between Antihistamines and Corticosteroids?

Both antihistamines and corticosteroids are aimed at diminishing immune system activity. However, the distinction between the two medications is in the chemical pathways they target. Antihistamines work on histamines to decrease their influence on the immune system and inflammatory processes. On the other hand, corticosteroids function by reducing the chemical reactions that cause inflammation upstream.

Side Effects

The following are the side effects of antihistamines and corticosteroids.

Antihistamines Side Effects

The adverse effects linked to antihistamine use are dependent on whether you are taking first or second-generation antihistamines, as well as whether you are taking H1 or H2 blockers. The side effects of nasal antihistamines may include sneezing and upper respiratory infections..3

First-generation are associated with the following common side effects:

  • Dry mouth and eyes
  • Rapid heart rate
  • Drowsiness or excessive fatigue
  • Vision problems
  • Low blood pressure
  • Mucus thickening in airways making it more difficult to breathe
  • 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 include:

Side effects of H2 blocker tend to be rare but may include:3

  • Fatigue or drowsiness
  • Tenderness or muscle pain, including breast swelling
  • Joint pains
  • Headache
  • Dizziness
  • Confusion can also occur in elderly patients

Corticosteroid Side Effects

Short-term side effects of taking corticosteroids include:7

  • Fluid retention causing swelling
  • Weight gain
  • High blood sugar (hyperglycemia)
  • Difficulty controlling diabetes

According to experts, glucocorticoids are beneficial for short-term use in most cases due to their anti-inflammatory properties. However, chronic and systemic usage of these drugs frequently results in side effects, including a decrease in sensitivity to the medication.

Long-term or high-dose use of corticosteroids can result in a variety of side effects, which may lead to other health complications, including:

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

Drug Interactions

It is important to be aware of the following drug interactions when taking antihistamines and corticosteroids. Prior to starting any new medication, it is recommended to speak with a healthcare provider.





Antihistamines have the potential to interact with other medications and substances, leading to 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

In addition to over-the-counter and prescription-strength medications, antihistamines may also interact with antipsychotics and certain medications used to prevent vomiting, such as Compro (prochlorperazine) and Promethazine DM (promethazine and dextromethorphan). It is important to discuss all medications and supplements being taken with a healthcare provider before starting antihistamine therapy.


Corticosteroids can interact with medications that impact the digestive system and metabolism, such as Nizoral (ketoconazole) and Norvir or Kaletra (ritonavir). It is important to review all medications and supplements being taken with a healthcare provider before starting corticosteroid therapy.


If you are unsure about whether a medication interacts with antihistamines or corticosteroids, it is recommended to consult with a healthcare provider, at TGH Urgent Care powered by Fast Track, to review your medication list.


It’s crucial to follow medical advice and directions when taking antihistamines or corticosteroids. Using multiple types of antihistamines simultaneously without medical consultation can be harmful and result in an overdose, leading to seizures, hallucinations, heart attacks, or even death. Additionally, antihistamines and corticosteroids may contain decongestants, which can increase the risk of overdose if taken in excess. Therefore, it’s important to read the labels of both old and new medications and avoid doubling the dosage without consulting a healthcare provider.


Antihistamines and corticosteroids both aim to reduce immune system activity, but they target different chemicals involved in the process. Antihistamines block histamine action caused by allergies, while corticosteroids work on other immune system and inflammatory chemicals.

There are different types of antihistamines, including first- and second-generation drugs as well as nasal antihistamines, and corticosteroids come in various forms, including synthetic corticosteroids and mineralocorticoids. Side effects of antihistamines depend on the type, with second-generation antihistamines having fewer side effects than first-generation drugs.

Corticosteroids can cause fluid retention and weight gain, among other side effects. It’s important to note that antihistamines can interact with other medications, such as antipsychotics and some anti-vomiting drugs, causing drowsiness. Corticosteroids may interact with drugs that affect metabolism. If you’re unsure about a certain medication interacting with an antihistamine or corticosteroid, it’s best to consult with a pharmacist or healthcare provider.


  • Can antihistamines and corticosteroids cause weight gain?

Yes, corticosteroids can cause weight gain and fluid retention. Antihistamines can also cause weight gain as a side effect, but it is less common.

  • Do antihistamines and corticosteroids have any interactions with food?

Antihistamines and corticosteroids can interact with grapefruit juice, which can increase the level of the medication in your blood and potentially cause side effects. It’s important to talk to your healthcare provider or pharmacist about any potential food interactions with your medication.

  • How long can you take antihistamines and corticosteroids for?

The length of time you can take antihistamines and corticosteroids will depend on your specific condition and symptoms. In general, antihistamines are safe for long-term use, but corticosteroids have more side effects and are typically used for short-term treatment of acute conditions. It’s important to follow your healthcare provider’s instructions for taking any medication.

  • What are the most common side effects of antihistamines?

The most common side effects of antihistamines include drowsiness, dry mouth, dizziness, and headache. First-generation antihistamines can also cause confusion, blurred vision, and urinary retention.

  • What are the most common side effects of corticosteroids?

The most common side effects of corticosteroids include weight gain, fluid retention, increased appetite, and mood changes. Long-term use can also lead to bone thinning and increased risk of infections.

  • How are antihistamines and corticosteroids different?

Antihistamines and corticosteroids have different mechanisms of action. Antihistamines are used to reduce histamine activity associated with allergies, while corticosteroids are used to reduce immune system activity associated with chronic inflammation.

  • Is it safe to take antihistamines and corticosteroids together?

In most cases, it is safe to take antihistamines and corticosteroids together, but it’s important to consult with your healthcare provider first. However, taking more than one antihistamine at a time can be dangerous unless under the direction of a medical provider.

  • Are antihistamines and corticosteroids safe during pregnancy?

Some antihistamines and corticosteroids may be safe to use during pregnancy, but it’s important to consult with your healthcare provider before taking any medication during pregnancy.

  • Which is better for nasal allergy, nasal steroids or antihistamines?

Research suggests that nasal steroids are more effective than antihistamines in reducing symptoms of nasal allergy, including sleep problems, daytime sleepiness, sneezing, itchiness, and congestion. Nasal steroids can be considered as the first option for treating nasal allergies.

  • Do antihistamines help reduce inflammation?

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

  • What is the best medicine for allergies?

The best medicine for allergies depends on the cause of the allergic reaction. Generally, second-generation antihistamines and nasal steroids are considered the best options. Consult with your healthcare provider at TGH Urgent Care powered by Fast Track for specific recommendations based on your health needs.

Disclaimer & References:

The information provided by TGH Urgent Care powered by Fast Track is backed by credible sources, such as peer-reviewed studies, to ensure accuracy and reliability. It is intended for educational and informational purposes only and is not a replacement for professional medical advice. For any concerns or inquiries about a medical condition, it is recommended to seek advice from a qualified healthcare provider.

  1. Cleveland Clinic. Antihistamines.
  2. Antihistamines for allergies.
  3. MedLine Plus. Antihistamines.
  4. American College of Obstetricians and Gynecologists. What medicine can I take for allergies while I’m pregnant?
  5. Malone M, Kennedy TM. Review: Side effects of some commonly used allergy medications (decongestants, anti-leukotriene agents, antihistamines, steroids, and zinc) and their safety in pregnancy. Int J Aller Medications. 2017;3:024.
  6. Gladness Dakalo Nethathe, Jeremy Cohen, Jeffrey Lipman, Ronald Anderson, Charles Feldman. Mineralocorticoid dysfunction during critical illness: A review of the evidenceAnesthesiology2020; 133:439–457 doi:10.1097/ALN.0000000000003365
  7. Gensler LS. Glucocorticoids: complications to anticipate and preventThe Neurohospitalist. 2013;3(2):92-97. doi:10.1177/1941874412458678
  8. Yang R, Yu Y. Glucocorticoids are a double-edged sword in the treatment of COVID-19 and cancersInt J Biol Sci. 2021;17(6):1530-1537. doi:10.7150/ijbs.58695
  9. Mayo Clinic. Antihistamine, decongestant, and analgesic combination (oral route).
  10. NHS Inform. Corticosteroids.
  11. Poison Control. Safe use of antihistamines.
  12. Berlin JM, Golden SJ, Teets S, Lehman EB, Lucas T, Craig TJ. Efficacy of a steroid nasal spray compared with an antihistamine nasal spray in the treatment of perennial allergic rhinitisJ Am Osteopath Assoc. 2000;100(7 Suppl):S8-S13.
  13. Hunto ST, Kim HN, Baek KS, Jeong D, Kim E, Kim JH, Cho JY. Loratadine, an antihistamine drug, exhibits anti-inflammatory activity through suppression of the NF-kB pathwayBiomedical pharmacology. 2020;177:113949. doi:10.1016/j.bcp.2020.113949

The blogs presented by TGH Urgent Care in partnership with Fast Track are not a replacement for medical care and are exclusively intended for educational purposes. The content provided here should not be construed as medical guidance. If you are encountering any symptoms, we strongly recommend that you seek an appointment with a duly qualified medical practitioner at our nearest facility.

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