Medicines & Supplements A to Z > Oxybutynin


Last updated on 13/07/2021.

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

GENERIC NAME: Oxybutynin



DRUG CLASS: Antispasmodics

SUB CLASS: Anticholinergics

USED FOR: Overactive bladder

AVAILABLE DOSAGE FORMS: 2.5mg, 5mg (tablets)

What is Oxybutynin for?

Oxybutynin belongs to a class of medications called anticholinergics. It works by inhibiting a chemical in your body to release the bladder muscles, so it is used for the treatment of overactive bladder.

How to use it?

Oxybutynin can be taken orally as tablets. 

5 mg twice or three times daily, up to maximum 5 mg four times daily if needed. 

Children ≥ 5 years of age:
2.5-5 mg twice daily, up to maximum 5 mg three times daily if needed.

2.5 mg twice daily, and can be increased to 5 mg twice daily if tolerated.

What are the side effects of Oxybutynin?

Common side effects of Oxybutynin include blurred vision, urinary tract infection, dizziness, headache, nausea, dry mouth, constipation, and urinary retention.

Who should not take Oxybutynin?

– People who are allergic to Oxybutynin or any component of the formulation
– Patients with or at risk for uncontrolled narrow-angle glaucoma, urinary retention, gastric retention or conditions with severely decreased GI motility

Pharmacist Tips:

– Avoid driving or other activities requiring clear vision until you know how you respond to this drug.
– Avoid alcohol while taking this medication.
– Be careful in hot weather or while being active because this drug may cause heat exhaustion more easily when used in a hot environment. 

Common dosing schedule:
Oxybutynin can be taken with or without food. 

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

Some common medications Oxybutynin may interact with:
– Anticholinergics, e.g. Ipratropium, Tiotropium
– Potassium, e.g. Potassium chloride, Potassium citrate
– Antibiotics, e.g. Clarithromycin, Erythromycin
– Antifungals, e.g. Itraconazole, Ketoconazole
– Dopamine antagonists, e.g. Metoclopramide, Domperidone

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

Where to buy Oxybutynin in Hong Kong?

In Hong Kong, Oxybutynin is a medicine under supervised sales and can be purchased under the supervision of a pharmacist from any pharmacies in Hong Kong. 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 Oxybutynin 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.