Antihistamines vs. Corticosteroids

• Antihistamines and corticosteroids are used to treat allergy symptoms such as itching, hives, skin rashes, and itchy or watery eyes.
• Antihistamines also may be used to treat motion sickness, insomnia (difficulty sleeping), and anxiety.
• Corticosteroids are also used for their strong anti-inflammatory effects to treat conditions such as arthritis, colitis, asthma, and bronchitis.
• Side effects of antihistamines and corticosteroids are different.
• Side effects of antihistamines that are different from corticosteroids include drowsiness, dry mouth, decreased tear production, trouble urinating, blurred vision, constipation, and agitation.
• Side effects of corticosteroids that are different from antihistamines include fluid retention (edema), high blood pressure, loss of potassium, headache, muscle weakness, puffiness of the face (moon face), facial hair growth, thinning and easy bruising of the skin, slow wound healing, glaucoma, cataracts, ulcers in the stomach and duodenum, loss of diabetes control, menstrual irregularity, and "buffalo hump" (rounding of the upper back).

• Antihistamines work by blocking the effects of a chemical called histamine that is responsible for many allergic symptoms such as congestion, runny nose, sneezing, itchy throat, hives, skin rashes, itching, and itchy or watery eyes. Antihistamines also may be used to treat motion sickness, insomnia (difficulty sleeping), and anxiety.
• Corticosteroids belonging to the glucocorticoid drug class are used mostly for their strong anti-inflammatory effects and in conditions that are related to the immune system function such as arthritis, colitis (ulcerative colitis, and Crohn's disease), asthma, bronchitis, some skin rashes, and allergic or inflammatory conditions involving the nose and eyes.

Antihistamine side effects

First generation antihistamines are used less often to treat allergies because they cause significant sedation. First generation antihistamines also should be used cautiously in older adults as they are more susceptible to their anticholingeric side effects including

• drowsiness,
• dry mouth,
• decreased tear production,
• urinary retention (trouble urinating),
• blurred vision,
• constipation, and
• agitation.

Due to their significant side effect profile, special precautions should be used in patients with:

• Seizures
• Glaucoma
• Problems passing urine or men with prostate problems
• Thyroid disorders
• High blood pressure
• Diabetes

Second generation antihistamines are less sedating than their first generation counterparts. Cetirizine can be sedating for some patients at normal recommended doses while sedation seems to only be a concern with loratadine at higher than normally recommended doses. Fexofenadine is the least sedating.

Side effects common to all antihistamines include:

• Dizziness
• Dry mouth
• Dry eyes
• Blurred vision
• Problems urinating
• Constipation
• Mental disturbances

Corticosteroid side effects

Corticosteroids have many side effects that can be mild or serious. These side effects are more apparent when corticosteroids are used at higher doses or for extended periods of time. This section lists only some of these side effects of corticosteroids.

Corticosteroids can:

• cause sodium (salt) and fluid to be retained in the body and cause weight gain or swelling of the legs (edema)
• High blood pressure
• Loss of potassium
• Headache
• Muscle weakness
• Puffiness of the face (moon face)
• Facial hair growth
• Thinning and easy bruising of the skin
• Slow wound healing
• Glaucoma
• Cataracts
• Ulcers in the stomach and duodenum
• Loss of diabetes control
• Menstrual irregularity
• "Buffalo hump," a condition described as a rounding of the upper back

Long-term use

The prolonged use of corticosteroids can cause obesity, growth retardation in children, and even lead to convulsions and psychiatric disturbances. Reported psychiatric disturbances include depression, euphoria, insomnia, mood swings, and personality changes. Psychotic behaviors also have been reported.

Corticosteroids, since they suppress the immune system, can lead to an increase in the rate of infections and reduce the effectiveness of vaccines and antibiotics.
The long term use of corticosteroids may cause osteoporosis which can result in bone fractures.

Shrinking (atrophy) of the adrenal glands can be caused by the long term use of corticosteroids resulting in the body's inability to produce cortisol, the body's natural corticosteroid, when the systemic corticosteroids are discontinued.

Another condition which can result from the long term use of corticosteroids is adrenal necrosis of the hip joints, a very painful and serious condition that may require surgery. Any symptoms of hip or knee pain in people taking corticosteroids require prompt medical attention.

Corticosteroids should not be stopped suddenly after prolonged use as this can result in adrenal crisis because of the body's inability to secrete enough cortisol to make up for the withdrawal. Nausea, vomiting, and shock are the reported side effects of adrenal crisis.

Antihistamine drug interactions

Antihistamines may cause drowsiness. Taking antihistamines with other medicines that also are sedating may cause profound drowsiness. Examples include:

• Sleeping pills
• Alcohol
• Seizure medications
• Some antidepressants (especially tricyclic antidepressants)
• Antipsychotics
• Muscle relaxants
• Prescription narcotic pain medications
• Other antihistamines
• MAOIs (monoamine oxidase inhibitors), a class of medications used to treat mood disorders, may prolong or intensify the anticholinergic side effects of antihistamines.

Generally, first generation antihistamines should not be used within two weeks of using a MAOI.

Corticosteroid drug interactions

• Certain drugs such as troleandomycin (TAO), erythromycin (Ery-Tab, EryPed 200), and clarithromycin (Biaxin) and ketoconazole (Nizoral) can reduce the ability of the liver to metabolize (breakdown) corticosteroids and this may lead to an increase in the levels and side effects of corticosteroids in the body. On the other hand, phenobarbital, ephedrine, phenytoin (Dilantin), and rifampin (Rifadin, Rimactane) may reduce the blood levels of corticosteroids by increasing the breakdown of corticosteroids by the liver. This may necessitate an increase of corticosteroid dose when they are used in combination with these drugs.
• Estrogens have been shown to increase the effects of corticosteroids possibly by decreasing their breakdown by the liver.
• Corticosteroid effects on warfarin can vary; therefore when taking warfarin (Coumadin) along with corticosteroids, there may be increased need for monitoring coagulation levels more closely.
• Low blood potassium (hypokalemia) and a higher chance of heart failure can result from combining corticosteroids with drugs that reduce potassium in the blood (for example, diuretics, amphotericin B).
• Anticholinesterase drugs (for example, physostigmine) may cause severe weakness in some patients with myasthenia gravis when prescribed with corticosteroids. Corticosteroids can increase blood glucose, so close monitoring of blood sugar and higher doses of diabetes medications may be needed.
• Cholestyramine (Questran, Questran Light) can decrease the absorption of oral corticosteroids from the stomach and this could reduce the blood levels of corticosteroids.

Antihistamines

First generation antihistamines include:

• brompheniramine
• chlorpheniramine (Chlor-Trimeton)
• diphenhydramine (Benadryl)
• doxylamine (found in many OTC sleep aids including Unisom)
• carbinoxamine (Karbinal ER)

Second generation antihistamines include:

• fexofenadine (Allegra)
• loratadine (Claritin)
• loratadine ODT (Alavert, Tavist ND)
• desloratadine (Clarinex)
• certirizine (Zyrtec)

Corticosteroids

The following is a list of the systemic (oral and injectable) corticosteroids that are available in the United States:

Glucocorticoids:

• hydrocortisone (Cortef)
• cortisone
• ethamethasoneb (Celestone)
• prednisone (Prednisone Intensol)
• prednisolone (Orapred, Prelone)
• triamcinolone (Aristospan Intra-Articular, Aristospan Intralesional, Kenalog) Methylprednisolone (Medrol, Depo-Medrol, Solu-Medrol)
• dexamethasone (Dexamethasone Intensol, DexPak 10 Day, DexPak 13 Day, DexPak 6 Day)

Mineralocorticoid:

• Fludrocortisone (Florinef)