Medicines & Supplements A to Z > Simethicone


Last updated on 18/03/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAMES:  Simethicone (Simeticone) / Activated Dimeticone (Dimethicone


BRAND NAME(S) IN HONG KONG: Air – X 氣立適, Enzyplex (also contains enzymes and vitamins), Gascon, Gasteel, Hydrosil, Phazin 化氣丸

DRUG CLASS: Antiflatulent

USED FOR: Relief of bloating, fullness and gas in the stomach 

– 40mg (tablets)
– 40mg, 80mg, 120mg (chewable tablets)

What is Simethicone for?

Simethicone belongs to a class of medications called antiflatulents and is used to treat gas retention in adults, and gas pains in children. Simethicone reduces surface tension and prevents the formation of gas bubbles in your stomach and intestines. It is often prescribed with an antacid medicine (e.g. Alexitol Sodium, Aluminum, Magnesium, Calcium) or medicines used to treat stomach spasms (e.g. Alverine, Pipenzolate, Dicycloverine).

Some medicines in Hong Kong will be labelled as containing the medicine Dimethicone. This is because Simethicone is an activated form of liquid dimethicones. Dimethicone is also used in a wide variety of cosmetics and skin products. For the use of Dimethicone in medicines applied onto the skin, see our summary of Dimethicone.

How to use it?

Simethicone is taken by mouth as chewable tablets, conventional tablets, capsules and suspension. 

The usual dosage of Simethicone for adults is 40-125 mg 3-4 times per day as needed. Some people may use a single dose of 160 or 500 mg after a meal. You should not use more than 500 mg of Simethicone per day.

The usual dosage of Simethicone in children will depend on your child’s weight and age. Typical doses range from 20-40 mg 4 times a day, after or with meals and at bedtime. Make sure to shake Simethicone drops (suspension) well. It can be added to water, infant formula, or other liquids.

For the dosage of topical dimethicone, see our expert summary about Dimethicone.

What are the side effects of Simethicone?

No significant side effects have been reported.

Who should not take Simethicone?

People who are allergic to Simethicone or other ingredients of the formulation.

Pharmacist Tips:

– Chew thoroughly before swallowing if you are taking a chewable tablet.
– Shake well before using suspension. 

Common dosing schedule:
Take Simethicone after food and at bedtime.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Simethicone may interact with:
Simethicone does not have known interactions with other drugs.

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Simethicone in Hong Kong?

In Hong Kong, Simethicone is an over-the-counter medicine which can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Simethicone in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.