Clemastine | Side Effects, Dosage, Uses & More
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Generic Name:

clemastine, Oral tablet

Generic Name:
Tavist Allergy

clemastine, Oral tablet

All Brands

  • Tavist Allergy
SECTION 1 of 5

Highlights for clemastine

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Clemastine is used to treat symptoms of allergic rhinitis, such as sneezing, runny nose, teary eyes, and itching. It’s also used to treat a type of mild allergic reaction associated with hives (urticaria) as well as a type of swelling under your skin from the buildup of fluid (angioedema).

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This drug comes as a tablet or syrup that you take by mouth.

3

This drug is only available as a generic drug.

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More common side effects of this drug include sleepiness; dizziness; lack of coordination; thick mucus; chest congestion; dry nose, mouth, and throat; and stomach upset.

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This drug can make you very drowsy. When you take this drug, you should not drive, operate heavy machinery, or do activities for which you need to be alert.

IMPORTANT INFORMATION

Use with certain depressant drugs

Avoid taking clemastine with alcohol or other central nervous system (CNS) depressant drugs. Other CNS depressant drugs include sleeping pills, anxiety medication, pain medication, muscle relaxants, seizure medications, and some drugs used to treat certain psychiatric conditions. Taking these drugs with clemastine may slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death.

Causes drowsiness

This drug can make you very drowsy. When you have taken clemastine, you shouldn’t drive, operate heavy machinery, or do other activities for which you need to be alert.

What is clemastine?

Clemastine is a prescription drug. It’s available as an oral tablet and as oral syrup. It’s only available as a generic drug.

It may be used as part of a combination therapy. This means you may need to take it with other medications.

Why it's used

Clemastine is used to treat symptoms of allergic rhinitis, such as sneezing, runny nose, teary eyes, and itching. It’s also used to treat a type of mild allergic reaction associated with hives (urticaria) as well as a type of swelling under your skin from the buildup of fluid (angioedema).

How it works

Clemastine belongs to a class of drugs called antihistamines or H1-receptor antagonists. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

More Details

How it works

Clemastine belongs to a class of drugs called antihistamines or H1-receptor antagonists. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

During an allergic reaction, histamine and other chemicals are released, causing symptoms such as sneezing, runny nose, teary eyes, itching, and hives. It works by blocking the action of histamine in your body when you’re exposed to certain substances that cause you to have an allergic reaction, such as pollen, pet dander, and mold.

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clemastine Side Effects

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More Common Side Effects

Some of the more common side effects that can occur with use of this drug include:

  • sleepiness

  • dizziness

  • lack of coordination

  • thick mucus

  • chest congestion

  • dry nose, mouth, and throat

  • stomach upset

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Tightness in your chest and wheezing

  • Low blood pressure. Symptoms can include:

    • lightheadedness
    • dizziness
    • fainting
  • Fast or irregular heartbeat

  • Severe allergic reaction. Symptoms can include: trouble breathing swelling of your throat or tongue

  • Trouble urinating

  • Blood abnormalities, such as hemolytic anemia (low red blood cell counts), thrombocytopenia (low platelet counts), or agranulocytosis (low white blood cell counts). Symptoms can include:

    • Hemolytic anemia
      • tiredness
      • dizziness
      • shortness of breath
      • chest pain
      • irregular heartbeat
      • pale skin
      • cold fingers and toes
      • yellowing of your skin and the whites of your eyes
      • abdominal pain
    • Thrombocytopenia
      • bruising
      • bleeding that lasts longer than normal
      • bleeding from minor cuts
      • nosebleeds
      • abnormally heavy menstrual flow
      • blood in urine
      • black, tarry stools
    • Agranulocytosis
      • fevers or infections
      • aches
      • chills
      • nausea
      • vomiting
  • Seizures

Pharmacist's Advice
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy
Clemastine may cause drowsiness. When you take this drug, you shouldn’t drive, operate heavy machinery, or do other activities for which you need to be alert.
Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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clemastine May Interact with Other Medications

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Clemastine can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Alcohol interaction

Drinking alcohol can increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, slowed heart rate, slowed breathing, and loss of consciousness, possibly leading to coma or death. You should not drink alcohol if you take this drug.

Medications that might interact with this drug

Antidepressants

When taken with clemastine, certain antidepressant drugs called monoamine oxidase inhibitors (MAOIs) can increase the drying effects of clemastine. This can cause dry mouth, blurry vision, and trouble urinating. You should not take these drugs together. These antidepressants include:

  • isocarboxazid
  • phenelzine
  • tranylcypromine

Anxiety drugs

When taken with clemastine, certain anxiety medications may increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death. These anxiety drugs include:

  • alprazolam
  • chlordiazepoxide
  • clonazepam
  • clorazepate
  • diazepam
  • hydroxyzine
  • lorazepam
  • oxazepam

Muscle relaxants

Taking certain muscle relaxants with clemastine may increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death. These muscle relaxants include:

  • baclofen
  • carisoprodol
  • chlorzoxazone
  • cyclobenzaprine
  • dantrolene
  • metaxalone
  • methocarbamol
  • orphenadrine
  • tizanidine

Pain drugs

Taking certain drugs used to treat pain with clemastine may increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death. These pain drugs include:

  • codeine
  • fentanyl
  • hydrocodone
  • hydromorphone
  • levorphanol
  • meperidine
  • methadone
  • morphine
  • oxycodone
  • oxymorphone
  • tramadol

Mental health (psychiatric) drugs

Taking certain drugs used to treat psychiatric conditions together with clemastine may increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death. These psychiatric drugs include:

  • First generation antipsychotics
    • chlorpromazine
    • fluphenazine
    • haloperidol
    • loxapine
    • perphenazine
    • thioridazine
    • thiothixene
    • trifluorperazine
  • Second generation antipsychotics
    • aripiprazole
    • asenapine
    • clozapine
    • iloperidone
    • lurasidone
    • olanzapine
    • paliperidone
    • quetiapine
    • risperidone
    • ziprasidone

Seizure drugs

Taking certain seizure drugs with clemastine may increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death. These seizure drugs include:

  • phenobarbital
  • pregabalin

Sleeping pills

Taking certain sleeping pills with clemastine may increase your risk of central nervous system (CNS) depression. CNS depression can slow down your brain activity to a level that causes an extreme effect on your body functions. This effect can cause extreme sleepiness, lack of coordination, impaired thinking, blurred vision, slurred speech, decreased heart rate, decreased breathing, and loss of consciousness, possibly leading to coma or death. These sleeping pills include:

  • chloral hydrate
  • estazolam
  • eszopiclone
  • flurazepam
  • temazepam
  • triazolam
  • zaleplon
  • zolpidem

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Clemastine warnings
People with angle-closure glaucoma
People with angle-closure glaucoma

Angle-closure glaucoma causes pressure inside your eye. If you have this condition and take this drug, you may cause a sudden and severe increase in that pressure. This is called acute angle-closure glaucoma. Acute angle-closure glaucoma is an emergency and may result in permanent vision loss. Talk to your doctor before you use this drug.

 People with digestive tract problems
People with digestive tract problems

If you have a history of blockage in your intestinal tract, you should talk to your doctor before using this drug. This drug can slow down the movement of food in your digestive tract. This increases your risk of blockage. Also, if you have a history of peptic ulcers, this drug can decrease the amount of certain substances that your intestines release that usually help relieve peptic ulcers.

People with prostate problems
People with prostate problems

This drug may make it more difficult to urinate. If you have difficulty urinating because you have an enlarged prostate, taking this drug may make urinating even more difficult.

People with bladder blockage
People with bladder blockage

This drug may make it more difficult to urinate. If you have difficulty urinating because you have bladder blockage, taking this drug may make urinating even more difficult.

People with chronic obstructive pulmonary disease (COPD)
People with chronic obstructive pulmonary disease (COPD)

If you have asthma or COPD, this drug may thicken the secretions in your breathing tubes. This may aggravate an asthma attack or COPD at a time when your symptoms are increased. This drug should not be taken during these times. You may be able to use it cautiously at other times. Talk to your doctor.

 People with hyperthyroidism
People with hyperthyroidism

If you have hyperthyroidism, this drug may aggravate your condition and caution should be used when taking this drug.

People with heart problems and high blood pressure
People with heart problems and high blood pressure

This drug may cause high blood pressure. It may also make your heart beat faster or skip a beat. If you have a history of high blood pressure or heart disease, taking this may make these issues worse.

Patients with liver problems
Patients with liver problems

If you have liver problems, more of this drug may stay in your body longer. You may have more side effects.

Pregnant women
Pregnant women

Clemastine is a category B pregnancy drug. That means two things:

  1. Research in animals has not shown a risk to the fetus when the mother takes the drug.
  2. There aren’t enough studies done in humans to show if the drug poses a risk to the fetus.

Talk to your doctor if you’re pregnant or planning to become pregnant. Animal studies do not always predict the way humans would respond. Therefore, this drug should only be used in pregnancy if clearly needed.

Women who are breast-feeding
Women who are breast-feeding

Clemastine may pass into breast milk and may cause side effects in a child who is breast-fed.

Talk to your doctor if you breast-feed your child. You may need to decide whether to stop breast-feeding or stop taking this drug.

For seniors
For seniors

This drug is more likely to cause side effects like dizziness, drowsiness, and low blood pressure in people 60 years and older.

For children
For children

Overdose of this drug in children is more likely to cause hallucinations, seizures, and death. Symptoms of overdose may include enlarged pupils that don’t get smaller, flushed face, dry mouth, fever, hallucinations, seizures, muscle contractions, and lack of coordination.

When to call the doctor
When to call the doctor

Call your doctor if you notice that your symptoms are not improving. Symptoms may include sneezing, runny nose, itching, eye tearing, or hives (swelling of your skin into red or skin-colored welts).

Allergies
Allergies

This drug can cause a severe allergic reaction. Symptoms can include:

  • trouble breathing
  • swelling of your throat or tongue

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it.Taking it again could be fatal (cause death).

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How to Take clemastine (Dosage)

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All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Allergic rhinitis

Generic: Clemastine

Form: oral tablet
Strengths: 2.68 mg
Form: oral syrup
Strengths: 0.5 mg clemastine/5mL
Adult dosage (ages 18 years and older):
  • Syrup:
    • The starting dose is 2 teaspoons (1 mg), twice daily.
    • Your dose may be increased to 12 teaspoons (6 mg) daily, depending on your response to the drug.
  • Tablet:
    • The starting dose is 1/2 tablet (1.34 mg), twice daily.
    • Your dose may be increased up to 1 tablet (2.68 mg), three times daily, depending on your response to the medication.
Child Dosage (ages 12–17 years):
  • Syrup:
    • The starting dose is 2 teaspoons (1 mg), twice daily.
    • Your dose may be increased to 12 teaspoons (6 mg) daily, depending on your response to the medication.
  • Tablet:
    • The starting dose is 1/2 tablet (1.34 mg), twice daily.
    • Your dose may be increased to 1 tablet (2.68 mg), three times daily, depending on your response to the medication.
Child Dosage (ages 6–11 years):
  • Syrup:
    • The starting dose is 1 teaspoon (0.5 mg), twice daily.
    • Your dose may be increased to 6 teaspoons (3 mg) daily, depending on your response to the medication.
  • Tablet: It hasn’t been confirmed that clemastine tablets are safe and effective for use in people younger than 12 years.
Child Dosage (ages 0–5 years):

It hasn’t been confirmed that this drug is safe and effective for use in people younger than 6 years.

Urticaria and angioedema

Generic: Clemastine

Form: oral tablet
Strengths: 2.68 mg
Form: oral syrup
Strengths:0.5 mg clemastine/5mL
Adult dosage (ages 18 years and older):
  • Syrup:
    • The starting dose is 4 teaspoons (2 mg), twice daily.
    • Your dose may be increased to 12 teaspoons (6 mg) daily, depending on your response to the medication.
  • Tablet:
    • The recommended starting dose is 1 tablet (2.68 mg), once daily..
    • Your dose may be increased to 1 tablet (2.68 mg), three times daily, depending on your response to the drug.
Child Dosage (ages 12–17 years):
  • Syrup:
    • The starting dose is 4 teaspoons (2 mg), twice daily.
    • Your dose may be increased to 12 teaspoons (6 mg) daily, depending on your response to the medication.
  • Tablet:
    • The starting dose is 1/2 tablet (1.34 mg), twice daily.
    • Your dose may be increased to 1 tablet (2.68 mg), three times daily, depending on your response to the medication.
Child Dosage (ages 6–11 years):
  • Syrup:
    • The starting dose is 2 teaspoons (1 mg), twice daily.
    • Your dose may be increased to 6 teaspoons (3 mg) daily, depending on your response to the medication.
  • Tablet: It hasn’t been confirmed that clemastine tablets are safe and effective for use in people younger than 12 years.
Child Dosage (ages 0–5 years):

It hasn’t been confirmed that this drug is safe and effective for use in people younger than 6 years.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

Colchicine comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug or don’t take it at all

Your symptoms such as sneezing, runny nose, itching, eye tearing, and hives (swelling of skin into red or skin-colored welts) may reoccur and worsen.

If you miss doses or don’t take the drug on schedule

Your medication may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

If you take too much

You could have dangerous levels of the drug in your body. If you think you’ve taken too much of the drug, act right away. Call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

An overdose of this drug in children is more likely to cause hallucinations, seizures, and death. Symptoms of overdose may include enlarged pupils that don’t get smaller, flushed face, dry mouth, fever, hallucinations, seizures, muscle contractions, and lack of coordination.

What to do if you miss a dose

Take your dose as soon as you remember. But if you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working

Your symptoms, such as sneezing, runny nose, itching, eye tearing, and hives (swelling of skin into red or skin-colored welts), should decrease or stop.

Clemastine is used for long-term treatment of allergic rhinitis.

Clemastine is used for short-term treatment of urticaria and angioedema.

Important considerations for taking Clemastine
You can take this drug with or without food. Taking it with food may help to reduce upset stomach.
You can take this drug with or without food. Taking it with food may help to reduce upset stomach.
You can cut or crush the tablet
You can cut or crush the tablet
Store this drug at room temperature below 77°F (25°C)
Store this drug at room temperature below 77°F (25°C)
See Details
A prescription for this medication is refillable
A prescription for this medication is refillable
See Details
Travel
Travel
See Details
Sun sensitivity
Sun sensitivity
See Details
Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead.
Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead.
Insurance
Insurance
See Details

Store this drug at room temperature below 77°F (25°C)

Keep it away from high temperatures.

Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Sun sensitivity

This drug may make you more sensitive to the sun. If you plan to be in the sun for a long time, you should take precautions. Wear sunscreen. Wear protective clothing. Limit the time that you spend in the sun.

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

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How Much Does clemastine Cost?

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Lowest price for clemastine

Walmart $26.18
Walgreens $26.67
Publix $32.34
These prices represent the lowest priced national pharmacies for clemastine on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for clemastine on GoodRx. They may be lower than your insurance.

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Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on November 17, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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