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.

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. 

Types

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

• Common cold symptoms
• Short-term insomnia
• Anxiety

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:

• 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 360 (famotidine)
  

What Are Corticosteroids?

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

Types

Glucocorticoids

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.

Examples of glucocorticoids include:

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

Mineralocorticoid​​

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)

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:

• 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:

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

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

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

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.

Summary

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.