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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Generic drug name: chlorpheniramine (klor fen EER a meen)
Brand name(s): ALERMINE, CHLOR-TRIMETON
GENERIC: available FAMILY: Antihistamines
Find the drug label by searching at DailyMed.

Generic drug name: chlorpheniramine injection
Brand name(s):
GENERIC: not available FAMILY: Antihistamines
Find the drug label by searching at DailyMed.

Generic drug name: diphenhydramine (di fen HYE dra meen)
Brand name(s): BENADRYL, DYTAN SUSPENSION, DYTAN-D SUSPENSION, SOMINEX FORMULA
GENERIC: available FAMILY: Antihistamines
Find the drug label by searching at DailyMed.

Generic drug name: diphenhydramine injection
Brand name(s):
GENERIC: not available FAMILY: Antihistamines
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy and Breast-feeding Warnings

There is no information in the labels for these drugs. Consult with your doctor or pharmacist if you already are or are planning to become pregnant or to breast-feed.

Safety Warnings For This Drug [top]

Anticholinergic Effects

Warning: Special Mental and Physical Adverse Effects

Older adults are especially sensitive to the harmful anticholinergic effects of these drugs. Drugs in this family should not be used unless absolutely necessary.

Mental Effects: confusion, delirium, short-term memory problems, disorientation and impaired attention

Physical Effects: dry mouth, constipation, difficulty urinating (especially for a man with an enlarged prostate), blurred vision, decreased sweating with increased body temperature, sexual dysfunction and worsening of glaucoma

Non-Drug Approaches to Allergies

Avoid exposure to things that trigger your allergies or asthma, such as animals, bedding, chemicals, cosmetics, drugs, dust, mold, foods, pollens, or smoke. Wearing a mask reduces inhalation of drugs, pollens, and smoke. Many people with mildly red, itching eyes require no treatment. Cold compresses to the eyes may prove helpful. Using eye drops with vasoconstrictors whitens eyes for a while, but rebound redness can occur. Misuse of vasoconstrictors sets up a vicious cycle.

Facts About This Drug [top]

Chlorpheniramine relieves the symptoms of hay fever and other allergic reactions. Diphenhydramine is used to treat allergic reactions, coughing, insomnia and motion sickness.

Do not use these drugs to treat a cold. Colds and allergies have different causes, and chlorpheniramine is not effective against either the cause of a cold or its symptoms. In fact, these drugs can make a cold or cough worse by thickening nasal secretions and drying mucous membranes.

These drugs can cause harmful...

Chlorpheniramine relieves the symptoms of hay fever and other allergic reactions. Diphenhydramine is used to treat allergic reactions, coughing, insomnia and motion sickness.

Do not use these drugs to treat a cold. Colds and allergies have different causes, and chlorpheniramine is not effective against either the cause of a cold or its symptoms. In fact, these drugs can make a cold or cough worse by thickening nasal secretions and drying mucous membranes.

These drugs can cause harmful adverse effects, most commonly in people over 60. These effects include confusion, dizziness or fainting; difficult or painful urination; dry mouth, nose or throat; nightmares; and unusual excitement, nervousness, restlessness or irritability. If you have any of these symptoms while taking chlorpheniramine, ask your doctor about changing your dose or discontinuing this drug. Since older people can be more sensitive to the usual adult dose, start with a low dose. This may decrease adverse effects.

In 2015, a study published in JAMA Internal Medicine showed that strong anticholinergic drugs such as chlorpheniramine and diphenhydramine were associated with an increased risk of dementia in older adults.[1],[2]

2020: The FDA issued an advisory that when patients take a higher-than-recommended dose of diphenhydramine, heart problems, seizures, coma or even death can occur.[3]

Before You Use This Drug [top]

Tell your doctor if you have or have had:

  • allergies to drugs
  • problems with urination
  • glaucoma
  • enlarged prostate
  • kidney problems
  • pregnancy or are breast-feeding

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Do not drink alcohol or use other drugs that can cause drowsiness.
  • Until you know how you react to this drug, do not drive or perform other activities requiring alertness.
  • If you plan to have any surgery, including dental surgery, tell your doctor that you take this drug.
  • Use sugarless gum, ice, or saliva substitutes if dry mouth develops.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Swallow tablets whole. Take at about the same time(s) each day.
  • Take with food, water, or milk.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Do not allow liquid form to freeze. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

alcohol, DILANTIN, phenytoin, RESTORIL, temazepam.

Antihistamines, when taken together with other drugs that affect the central nervous system (CNS), will cause additional drowsiness.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • cough
  • difficulty swallowing
  • dizziness
  • hives
  • itching
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • shortness of breath
  • skin rash
  • tightness in chest
  • unusual tiredness or weakness
  • wheezing
  • abdominal or stomach pain
  • chills
  • clay-colored stools or dark urine
  • fever
  • headache
  • fast or irregular heartbeat

Call your doctor if these symptoms continue:

  • gastrotintestinal upset (diphenhydramine)
  • clumsiness or unsteadiness
  • stomach pain or nausea (diphenhydramine)
  • blurred or any change in vision (diphenhydramine)
  • drowsiness
  • constipation
  • increased sweating (chlorpheniramine)
  • diarrhea
  • loss of appetite (chlorpheniramine)
  • dizziness
  • nightmares (diphenhydramine)
  • unusual excitement (both)
  • painful or difficult urination (chlorpheniramine)
  • nervousness or restlessness (both)
  • change in menstrual cycle
  • thickening of mucus (diphenhydramine)
  • confusion (diphenhydramine)

Signs of overdose:

  • clumsiness or unsteadiness
  • severe dry mouth, nose, or throat
  • flushed or red face
  • shortness of breath
  • trouble breathing
  • fast or irregular heartbeat
  • severe drowsiness
  • seizures
  • hallucinations
  • trouble sleeping
  • faintness or lightheadedness

If you suspect an overdose, call this number to contact your poison control center: (800) 222-1222.

last reviewed February 28, 2021