Safely Buy Theo Dur ( Theophylline SR ) from Canada Prescriptions Plus.

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Theophylline SR

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Formulation : 12H ER Scored Tablet
Drug Name Dosage Quantity Price Buy Now
Theophylline SR 100mg 100 $38.95 Add To Cart
Theophylline SR 200mg 100 $40.90 Add To Cart
Theophylline SR 300mg 100 $44.80 Add To Cart
Theophylline SR
Dosage: 100mg
Quantity: 100
Price: $38.95
Theophylline SR
Dosage: 200mg
Quantity: 100
Price: $40.90
Theophylline SR
Dosage: 300mg
Quantity: 100
Price: $44.80


Theo Dur is a respiratory medication used to treat lung disorders such as asthma, bronchitis, and emphysema.

Theophylline is a bronchodilator that relaxes smooth muscles in your respiratory system and inhibits your body’s response to stimulation in the airway to help prevent bronchospasm attacks and other constrictions. These actions help Theo Dur treat breathing issues like asthma and bronchitis while improving air flow and offering some protection against future attacks.

Dosage and Administration

The dose of Theo Dur that is prescribed will vary depending on the individual and breathing condition being treated. Follow all your healthcare provider’s instructions and read packaging labels carefully to ensure the best results during treatment. Do not change your dose on your own or take Theo Dur for longer than prescribed.

  • Swallow tablets whole, do not crush or chew
  • Take doses at the same times each day
  • Can be taken with or without food but take the same way each time
  • Store at room temperature away from children and pets

Adults and children weighing over 45kg:

  • Most start by taking 300 to 400mg once daily
  • After 3 days of initial treatment, doses may increase up to 400 to 600mg a day
  • Doses may increase once again after another 3 days if tolerated to no more than 600mg daily

Children weighing less than 45kg:

  • Most children take 12 to 14mg/kg each day up to a maximum of 300mg daily
  • After 3 days, doses may be increased to 16mg/kg daily up to 400mg a day if tolerated
  • Following another 3 days of treatment, if needed and tolerated doses can increase to 20mg/kg a day but no more than 600mg daily

Side Effects

Theo Dur may cause some side effects to develop during treatment while relaxing your smooth muscle in your airways. Speak with your healthcare provider to learn more about any symptoms that you may encounter.

Common Theo Dur side effects:

  • Nausea, vomiting, diarrhea
  • Headache
  • Trouble sleeping
  • Tremors
  • Sweating
  • Restlessness, feeling irritable

Serious Side Effects

Some more serious adverse reactions may occur when taking Theo Dur to improve your breathing conditions. Stop using this medication and contact your healthcare provider if you notice any of the following symptoms:

  • Severe or prolonged vomiting
  • Ongoing headache, insomnia
  • Rapid heartbeats
  • Seizure
  • New signs of an illness, fever
  • Low levels of potassium (leg cramps, constipation, irregular heartbeat, fluttering sensation in your chest, increased thirst or urination, numbness or tingling, weakness)
  • High blood sugar levels (increased thirst, increased urination, dry mouth, fruity breath odour)

Older adults who take Theo Dur may be more likely to develop serious side effects.

Allergic Reactions

Do not take Theo Dur if you are allergic to theophylline, xanthine drugs, or any of the other tablet ingredients. If you notice signs of an allergic reaction during treatment, stop using this bronchodilator and call your healthcare provider.

Theo Dur allergy symptoms may include:

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


Do not take Theo Dur if you have any of the following conditions:

  • Active peptic ulcer disease
  • Seizure disorders like epilepsy
  • Cardiac arrhythmias other than bradyarrhythmia

To ensure your safety when taking this medication, tell your healthcare provider if you have ever had any of the following:

  • Stomach or intestinal ulcers
  • Seizures
  • Thyroid disease
  • Heart issues such as heart failure or irregular heartbeats
  • Liver disease
  • Kidney disease
  • High blood pressure
  • Serious infection known as sepsis
  • Fluid in your lungs

If you become sick or develop a fever during treatment with Theo Dur, tell your healthcare provider right away because your dose may need to be adjusted.

Contact your healthcare provider immediately if you notice that your breathing condition worsens quickly or if you think Theo Dur is not working as well.

Avoid smoking during treatment with Theo Dur because it can decrease the concentrations of the medications and reduce its efficacy.

Avoid drinking caffeine and alcohol while taking this medication because they can increase side effects of Theo Dur.

Children who take Theo Dur may be more vulnerable to developing side effects during treatment.

Tell your healthcare provider if you are pregnant or plan to become pregnant during treatment with Theo Dur. Discuss the risks and benefits of taking this medication during pregnancy. Doses may need to be adjusted, especially during the last 3 months of pregnancy.

Consult with your healthcare provider before breastfeeding while taking Theo Dur because the medication passes into breast milk and may affect your nursing child.

Some drugs may interact with Theo Dur and cause adverse reactions. Tell your healthcare provider about all the medications you take, including over the counter medicines, but especially any of the following:

  • Riociguat
  • Cimetidine
  • Disulfiram
  • Fluvoxamine
  • Interferon
  • Mexiletine
  • Propranolol
  • Rifampin
  • Seizure medications (carbamazepine, phenytoin, and others)
  • St. John’s wort
  • Ticlopidine
  • Viloxazine
  • Medications containing aminophylline or oxtriphylline

Form and Strength

This bronchodilator medication is available in the form of 12 hour sustained-release tablets.

Theo Dur SR tablet strengths:

  • 100mg
  • 200mg
  • 300mg

All Theo Dur tablet strengths are available in quantities of 100.


What not to do while taking Theo Dur?

During treatment with Theo Dur, you should avoid drinking high amounts of caffeine or alcohol because these can cause an increase in adverse effects. You should also avoid smoking while taking this medication because it can reduce Theo Dur’s effectiveness by decreasing its concentrations in your system. Follow all your healthcare provider’s directions for the best therapeutic response.

Does Theo Dur affect sleep?

A common side effect of Theo Dur is troubles sleeping, but this reaction may be avoided by taking your dose earlier in the day. However, some patients who experience asthma and other breathing issues during the night may experience better sleep because this medication reduces attacks. Speak with your healthcare provider for an individualized administration regimen.



Additional information

Brand Name:

Theo Dur

Scientific Name:

Theophylline SR

Other Names:

Theo LA, Theo La


100mg, 200mg, 300mg

Quantities Available:



12H ER Scored Tablet