> Western Medicines > Slo-Theo


What is Slo-Theo?

Slo-Theo is a brand medication that contains Theophylline, which belongs to a class of medications called phosphodiesterase (PDE) inhibitors. It works as a bronchodilator by relaxing the muscles of the airways and opening up the airways in the lungs making breathing easier. It is therefore used to treat asthma, chronic obstructive pulmonary disease (COPD), and bronchoconstriction by relieving symptoms of shortness of breath like breathlessness, coughing and wheezing.

How to use it?

Slo-Theo is available as extended-release capsules. Swallow whole and do not crush or chew them. The dosage schedule is to be given two doses in a day.

For Asthma, chronic obstructive pulmonary disease (COPD), bronchoconstriction, 
Initially 5-8mg/kg/day. Usual effective dose: 7-12mg/kg/day. Max daily dose: 800mg.  

Children 9-16 years 
Initially 10-12mg/kg/day. Usual effective dose: 10-16mg/kg/day. 

Children 30 months to 8 years 
Initially 10-14mg/kg/day. Usual effective dose: 13-20mg/kg/day. 

What are the side effects of Slo-Theo?

Common side effects of Slo-Theo include nauseavomitingheadacheinsomnia, tremor, restlessness, and irregular heartbeats.

Who should not take Slo-Theo?

People who are allergic to Slo-Theo or any component of the formulation.

Pharmacist Tips:

  • Do not break, chew or open sustained-release preparations. Swallow whole with water. 
  • If you have recently started or stopped smoking, it can alter the Slo-Theo level in the body and require dosage adjustments.

Common dosing schedule: 
Slo-Theo can be taken with or without food. Take it at the same time every day.

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


Some common medications Slo-Theo may interact with:

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

Where to buy Slo-Theo in Hong Kong?

In Hong Kong, Slo-Theo is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. 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 https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Slo-Theo 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.

Available dosage
  • 50mg / 100mg (Extended-Release Capsules)
Drug class
Sub class
Phosphodiesterase Inhibitors
Generic Names
Other drugs in same class
Used for: Prevention of thromboembolic events
Chinese name:
Used for: Erectile dysfunction, Pulmonary arterial hypertension, Benign Prostatic Hyperplasia (BPH)
Chinese name:
Used for: Prevention of thromboembolic events
Chinese name: