Clemastine fumarate is a first-generation antihistamine. It's used in adults and children for short-term relief of allergy symptoms, such as sneezing and runny nose. It can also help ease itchiness from chronic (long-term) hives or angioedema. Clemastine is only available by prescription, and comes as a tablet and syrup that's typically taken up to 3 times per day. Common side effects include sleepiness and dizziness. Brand name Tavist has been discontinued.
Clemastine is a first-generation antihistamine. It blocks a natural substance in your body called histamine. In doing so, clemastine lowers inflammation and relieves runny nose, itchy nose, and sneezing.
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Less common or rare
Less common or rare with azatadine, cetirizine, clemastine, cyproheptadine, desloratadine, dexchlorpheniramine, diphenhydramine, or loratadine
Abdominal or stomach pain
burning
chills
clay-colored stools or dark urine
difficulty swallowing
dizziness
fast or irregular heartbeat
headache
prickly sensations
puffiness or swelling of the eyelids or around the eyes, face, lips or tongue
redness of skin
seizures
shortness of breath
skin rash
swelling
tightness in chest
tingling
unusual tiredness or weakness
Check with your doctor as soon as possible if any of the following side effects occur:
Symptoms of overdose
Clumsiness or unsteadiness
convulsions (seizures)
drowsiness (severe)
dryness of mouth, nose, or throat (severe)
feeling faint
flushing or redness of face
hallucinations (seeing, hearing, or feeling things that are not there)
shortness of breath or troubled breathing
trouble in sleeping
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Drowsiness
dry mouth, nose, or throat
gastrointestinal upset, stomach pain, or nausea
headache
increased appetite and weight gain
thickening of mucus
Less common or rare
Acid or sour stomach
belching
blurred vision or any change in vision
body aches or pain
clumsiness or unsteadiness
confusion (not with diphenhydramine)
congestion
difficult or painful urination
difficulty in moving
difficult or painful menstruation
dizziness (not with brompheniramine or hydroxyzine)
drowsiness (with high doses of desloratadine and loratadine)
dryness of mouth, nose, or throat
early menstruation
fast heartbeat
hoarseness
increased sensitivity of skin to sun
increased sweating
indigestion
loss of appetite
joint pain
muscle aching or cramping
muscle pains or stiffness
nightmares (not with azatadine, chlorpheniramine, cyproheptadine, desloratadine, hydroxyzine, or loratadine)
ringing or buzzing in ears
skin rash
swollen joints
stomach discomfort, upset or pain
tender swollen glands in neck
unusual excitement, nervousness, restlessness, or irritability
vomiting
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
For the clemastine 0.5 mg/5 mL syrup:
Clemastine is still available in the United States by prescription from your healthcare professional (HCP) as a tablet that contains 2.68 mg of clemastine, as well as a syrup that contains 0.5 mg of clemastine in each 5 mL. But the over-the-counter tablet that contained 1.34 mg of clemastine has been discontinued.
No, both clemastine 2.68 mg tablets and 0.5 mg/5 mL syrup are currently only available in the United States by a prescription from an HCP. There isn't any other over-the-counter version of clemastine available.
Yes, clemastine can make you feel drowsy (sleepy). It's recommended to avoid drinking alcohol because it can make drowsiness and dizziness more intense. Don't drive or do anything that requires concentration until you know how this medication affects you. Contact your primary care provider to discuss better treatment options for your allergy symptoms if clemastine is making you too sleepy and affecting your daily activities.
Both clemastine and hydroxyzine (Vistaril) are first-generation prescription antihistamines, but they're not the same. One of the main differences between them is what conditions they're approved to treat. Clemastine is used for allergy symptoms and skin problems from hives or angioedema. Hydroxyzine (Vistaril) can also help with itchy skin from hives, but it's also approved for anxiety and is sometimes prescribed as a sedative during anesthesia. Talk to a healthcare professional (HCP) if you have more questions about the differences of these 2 medications.
Clemastine isn't FDA-approved to treat multiple sclerosis (MS). A small study suggests that clemastine might repair the damaged myelin and improve electrical signaling in nerves of people with MS. But more research is needed in this area.
Clemastine can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Clemastine can make you very sleepy, which can affect your ability to focus, think, or react. This side effect is more likely to happen or be more intense if you're 65 years or older, drink alcohol while taking this medication, or take other medications that cause sleepiness (e.g., opioids, benzodiazepines, sleep medications). Don't drive or operate machinery until you know how clemastine affects you.
People aged 65 years and older experience more side effects when taking antihistamine medications like clemastine. Watch out for changes in vision, severe dry mouth, trouble urinating, or constipation. Also, feelings of drowsiness can leave you unsteady on your feet, which can lead to accidental falls and injuries. Talk with your HCP before using clemastine.
Clemastine tablet: Each tablet contains 2.68 mg of clemastine.
Clemastine syrup: Each 5 mL contains 0.5 mg of clemastine.
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.
Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Clemastine will not be safe for you to take.