Clemastine: What is it? Uses, Instructions for Use, Side Effects and Precautions

It is an antihistamine used to relieve allergy symptoms, hay fever, and the common cold.

Uses of Clemastine

These symptoms include a rash, watery eyes, itchy eyes/nose/throat/skin, cough, runny nose, and sneezing.

This medication works by blocking a particular natural substance (histamine) that your body makes during an allergic reaction.

Blocking another natural substance produced by the body ( acetylcholine ) helps dry some body fluids to relieve symptoms such as watery eyes and runny nose.

It has not been demonstrated that products with and without cough are safe or effective in children under six. Therefore, do not use this product to treat cold symptoms in children under six unless specifically directed by the doctor.

Some products (such as long-acting pills/capsules) are not recommended for children under 12. Consult your doctor or pharmacist for more information about the safe use of your product.

These products do not cure or shorten the duration of the common cold and can cause serious side effects.


To reduce the risk of severe side effects, carefully follow all dosage instructions. Do not use this product to make the child sleepy.

Do not give other cough and cold medicines that may contain the same ingredients or similar ingredients (see also the Interactions with other medicines section).

Ask your doctor or pharmacist about other ways to relieve cough and cold symptoms (such as drinking enough fluids, using a humidifier, or saline drops/sprays).

How to use

If you are taking an over-the-counter medication, read all instructions on the product package before taking this medication. If you have any questions, ask your pharmacist.

If your doctor has prescribed this medication, take it as directed. Take the tablet or liquid by mouth with or without food. Follow the instructions for dosing on the label or handle as directed by your doctor.

This medicine can be taken with food or milk if a stomach upset occurs. Using the liquid, use a medication measuring device to measure the prescribed dose carefully.

Do not use a domestic spoon. Your dosage will depend on your age, medical condition, and response to therapy.

Do not increase your dose or take this medication more often than recommended by your doctor or the package instructions without your doctor’s approval.

Take this medication regularly to get the most benefit from it. To remember, take it at the same time every day. If your condition persists or worsens, or if you think you may have a severe medical problem, seek immediate medical attention.

Side Effects of Clemastine

Drowsiness, dizziness, headache, constipation, upset stomach, blurred vision, difficulty walking / clumsiness, or dry mouth/nose/throat may occur.

To relieve dry mouth, suck on candy (without sugar) or ice chips, chew gum (no sugar), drink water, or use a saliva substitute.

Clemastine can dry out and thicken the mucus in your lungs, making it harder to breathe and clean your lungs. To help prevent this effect, drink plenty of fluids unless your doctor tells you otherwise.

If your doctor has prescribed this medication, remember that they have determined that your benefit is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if you have any of these unlikely but serious side effects:

Mental / mood changes (hallucinations, irritability, nervousness, confusion), ringing in the ears, and difficulty urinating.

Tell your doctor immediately if you have any rare but severe side effects: easy bruising / bleeding, fast/irregular heartbeat, seizures.

It is unlikely that a severe allergic reaction to this drug will occur.

However, seek immediate medical attention if you notice any symptoms of a severe allergic reaction, including rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, or trouble breathing.


Before taking clemastine, tell your doctor or pharmacist if you are allergic to it or have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems.

Consult your pharmacist for more information.

Before using this medication, tell your doctor or pharmacist your medical history, especially about:

Respiratory problems (asthmaemphysema ), specific eye problems ( glaucoma ), heart problems, high blood pressure, liver disease, seizures, and stomach problems.

Also ulcers, obstruction, overactive thyroid ( hyperthyroidism ), and urination problems (such as difficulty urinating due to enlarged prostate and urinary retention).

This medicine may cause dizziness, drowsiness, or blurred vision. Do not drive, use machinery or perform activities that require alertness or a clear vision until you are sure you can achieve those activities safely.

Limit the use of alcohol and certain other medications that cause drowsiness. (Also see Interactions with other medicines).

To minimize dizziness and lightheadedness, get up slowly when you get up while sitting or lying down. The liquid preparations of this product may contain sugar and alcohol.

Caution is advised if you have diabetes, alcohol dependence, or liver disease. Ask your doctor or pharmacist about the safe use of this product.

Older adults may be more sensitive to the side effects of this medication, especially drowsiness, constipation, trouble urinating, or confusion.

Drowsiness and confusion can increase the risk of falls. Children may be more sensitive to the effects of antihistamines. This medication may cause agitation/excitement in young children instead of drowsiness.

During pregnancy, this medication should be used only when necessary. Talk to your doctor about the risks and benefits. This medicine passes into breast milk and may have undesirable effects on the infant. Consult your doctor before breastfeeding.