Theo Dur (Theophylline SR) Medication

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Drug Description


Theo Dur is a prescription medicine used for preventing and treating wheezing, shortness of breath, and chest tightness associated with asthma, chronic obstructive pulmonary disease (COPD, including bronchitis and emphysema), and other lung conditions. 

Classified as a xanthine drug, Theo Dur functions by inducing relaxation in the airway muscles, facilitating easier breathing. Moreover, it mitigates the lungs’ sensitivity to irritants. 

Uses and Dosage 

Before taking Theo Dur and with every prescription refill, carefully review its medication guide and patient information leaflet. If you have any queries, consult your doctor or pharmacist for guidance. 

The dosage of this medication may vary per individual based on their medical condition, response to treatment, age, weight, theophylline blood levels (as indicated by lab tests), and concurrent medication intake. 

Your doctor may advise you to begin taking Theo Dur at a low dose and then gradually increase it to minimize the chances of experiencing side effects. Carefully adhere to your doctor’s instructions. 

Typically, Theo Dur is taken every 12 hours with a full glass of water on an empty stomach, either at least 1 hour before or 2 hours after a meal. 

Do not cut the tablets unless your doctor advises it. Swallow the whole or split tablet without crushing or chewing, as this can lead to a sudden release of all the medication, raising the risk of side effects. 

Continue taking this medication at around the same time every day, even if you are in good health. Consult your doctor prior to making any changes, such as increasing the dosage or frequency or discontinuing usage. 

Seek immediate medical assistance if your asthma symptoms deteriorate or if you find yourself using your quick-relief inhaler more frequently or beyond the prescribed usage. 

Side Effects 

Listed below are the potential adverse effects of Theo Dur. Promptly notify your doctor if any of them persist or worsen. 

Common Side Effects 

  • Nausea, vomiting, diarrhea 
  • Headache 
  • Sleep problems (insomnia) 
  • Tremors 
  • Sweating 
  • Restlessness or irritability 

Serious Side Effects 

  • Severe or persistent vomiting 
  • Persistent headache and sleep difficulties 
  • Rapid heart rate 
  • Seizure 
  • New symptoms of illness, particularly fever 
  • Low potassium levels:  
    • Leg cramps 
    • Constipation 
    • Irregular heartbeats 
    • Chest fluttering 
    • Increased thirst or urination 
    • Numbness or tingling 
    • Muscle weakness 
    • Limpness 
  • High blood sugar:  
    • Increased thirst 
    • Increased urination 
    • Dry mouth 
    • Fruity breath odor 

Call your doctor right away if any of the serious side effects listed above are experienced. 

Allergic Reactions 

Although rare, a severe allergic reaction to Theo Dur may occur. Prompt medical attention must be sought in case of any signs of an allergic reaction, such as: 

  • Hives 
  • Difficulty breathing 
  • Swelling of the mouth, face, lips, tongue, or throat 

Not all side effects of Theo Dur are included in this list. Tell your doctor If any unlisted symptoms occur. 


Before starting treatment with Theo Dur, inform your doctor if you have any known allergies, particularly to theophylline or other xanthine drugs (e.g., aminophylline, oxtriphylline, caffeine) 

Seek further guidance from your pharmacist regarding Theo Dur, as it might contain inactive ingredients capable of inducing allergic reactions or other complications. 

To ensure Theo Dur is safe for you, disclose to your physician your medical background, especially if you have a history of: 

  • Gastrointestinal ulcer 
  • Seizures 
  • Thyroid disorders 
  • Heart conditions (e.g., heart failure, irregular heartbeat) 
  • Liver disease 
  • Hypertension (high blood pressure) 

Some products may interact with Theo Dur, including riociguat.To mitigate the risk of such drug interactions, inform all healthcare providers of any current or recently started or stopped medications, including prescription and over-the-counter drugs, vitamins, and herbal supplements. 

Other medications can impact the elimination of Theo Dur, altering its effectiveness. 

Examples of such medicines include: 

  • Cimetidine 
  • Disulfiram  
  • Fluvoxamine  
  • Interferon 
  • Mexiletine 
  • Propranolol 
  • Rifampin  
  • Antiseizure drugs (e.g., carbamazepine, phenytoin)  
  • St. John’s wort 
  • Ticlopidine  
  • Viloxazine 

Theophylline closely resembles aminophylline and oxtriphylline. Avoid using medications that contain aminophylline or oxtriphylline while taking Theo Dur. 

Smoking cigarettes or marijuana can lower Theo Dur’s blood levels. Inform your doctor if you are a smoker or have recently quit smoking. 

Specific diets (e.g., high protein/low carbohydrate or high carbohydrate/low protein) can alter the impact of Theo Dur. Inform your doctor of significant dietary changes, as dose adjustments may be necessary. 

Furthermore, promptly inform your doctor if you become ill or develop a fever while using this medication. It may be necessary to adjust your medication dosage. 

Consuming excessive amounts of alcohol or caffeine can exacerbate the adverse effects of Theo Dur. Abstain from consuming significant quantities of alcoholic or caffeinated beverages (e.g., coffee, tea, colas), indulging in large amounts of chocolate, or using over-the-counter products containing caffeine. 

Theo Dur can potentially affect specific lab tests (e.g., blood sugar, cholesterol, uric acid, dipyridamole-thallium imaging tests), leading to inaccurate results. Ensure that laboratory staff and healthcare providers know your Theo Dur usage. 

Elderly individuals may exhibit increased sensitivity to Tho Dur’s side effects, particularly rapid/irregular heartbeats or insomnia. Close monitoring of side effects and drug blood levels is advisable. 

Closely monitor the side effects and drug blood levels in children, as they may be more susceptible to the adverse reactions of Theo Dur. 

Theo Dur should only be used during pregnancy if absolutely necessary. Consult with your doctor to evaluate the potential risks and benefits. The drug’s concentration in your bloodstream may be influenced by bodily changes in the final trimester, so close monitoring by your doctor is essential to adjust the dosage if required. 

Theophylline can enter breast milk and potentially harm a nursing baby. Seek guidance from your doctor before breastfeeding. 

Additional information

Generic name:

Theophylline SR


12H ER Scored Tablet


100mg, 200mg, 300mg

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Quality Prescription Drugs has provided information from third parties intended to increase awareness and does not contain all the information about Theo Dur (Theophylline SR). Talk to your doctor or a qualified medical practitioner for medical attention, advice, or if you have any concerns about Theo Dur (Theophylline SR).