Theophylline and Guaifenesin (Oral)

Predominantly used to treat emphysema and chronic bronchitis, Theophylline and Guaifenesin is also used to treat and prevent the symptoms associated with asthma.


When used as a combination medicine, Theophylline and Guaifenesin helps to relieve symptoms such as shortness of breath, wheezing, coughing and trouble breathing. Due to this, it is used to treat a variety of respiratory conditions.

Although Theophylline can be given as an emergency medicine in a clinical setting, it is normally given intravenously in these circumstances. Most commonly, Theophylline is prescribed and given to patients to take at home in tablet or capsule form.

Classified as a bronchodilator, Theophylline works by relaxing the muscles in the chest and lungs. This encourages the airways to open more easily and, as a result, air can flow through the lungs and airways more easily. Due to its effect as a muscle relaxant, Theophylline is extremely helpful for patients whose respiratory conditions are preventing them from breathing easily.

Guaifenesin is also given to patients who are suffering from respiratory issues but it works in a different way. As an expectorant, Guaifenesin loosens congestion. Many patients with bronchitis and emphysema have trouble breathing due to congestion in their chests or throats. By easing this congestion, Guaifenesin helps to reduce troubled breathing.

While both drugs are effective in their own right, their effects can be increased when they are used in conjunction with one another. Prescribing Theophylline and Guaifenesin as a combination medication provides patients with two active ingredients and, therefore, two forms of symptom relief.

Conditions Treated

Type of Medicine

  • Theophylline:
    • Bronchodilator
  • Guaifenesin:
    • Expectorant

Side Effects

When taking any medication, it's important to be aware of the potential side effects which could occur. While some side-effects are expected to reduce during the course of treatment, some may require immediate medical attention. If the patient experiences the following side effects when taking Theophylline and Guaifenesin, they should contact their physician as soon as possible:

  • Heartburn
  • Behavioral changes
  • Abdominal pain
  • Confusion
  • Vomiting
  • Trembling
  • Nervousness
  • Restlessness
  • Low potassium
  • Irregular heartbeat
  • Diarrhea
  • Dark or bloody vomit
  • Confusion
  • High blood sugar
  • Rapid heartbeat

The following side effects have been associated with Theophylline and Guaifenesin but do not typically require urgent medical attention:

  • Headache
  • Increased urination
  • Sweating
  • Nervousness
  • Difficulty sleeping
  • Nausea

If any of the above side effects are severe or prolonged, however, the patient should seek medical help.


Theophylline and Guaifenesin is available in various formats and will be prescribed in the most appropriate way for the individual patient. While the medication is available as a liquid, elixir and syrup, it is most commonly prescribed as a tablet, capsule or a liquid-filled capsule. Theophylline and Guaifenesin is also available in an extended-release format.

When taking any medication, including Theophylline and Guaifenesin, it's vital that patients follow the instructions given by their physician. While there are typical dosage strategies, these should not replace the unique instructions given to the patient.

In general, Theophylline and Guaifenesin works best if it is taken on an empty stomach, with a glass of water. This means that patients should aim to take Theophylline and Guaifenesin 30 minutes to one hour before a meal or at least two hours after consuming a meal.

Various strengths of Theophylline and Guaifenesin are available. Common doses of this medication are 150mg-200mg in tablet form, 150mg-90mg in capsule form, 300mg-180mg also in capsule form, 100mg-100mg given as 15ml oral liquid and 150mg-90mg given as 15mg oral elixir.

Although Theophylline and Guaifenesin is a combination medication, the patient's symptoms may indicate the requirement for more of one active ingredient. Common capsule strengths are 150mg-90mg and 300mg-180mg, for example. In each preparation, the patient would receive 150mg or 300mg of Theophylline and 90mg or 180mg of Guaifenesin, respectively.

Making the medication available in various formats and at various strengths ensures that physicians can prescribe a suitable dose for each individual. Elderly patients may react more strongly to medication, for example, so a lower starting dose may be given.

Similarly, if children are prescribed Theophylline and Guaifenesin, physicians will determine their dose using various factors. Their age, weight and symptoms will be used to decide what strength of medication is appropriate.

In many instances, doctors will provide a relatively low starting dose of Theophylline and Guaifenesin and increase the dose if the patient's symptoms persist.

As Theophylline and Guaifenesin is designed to provide ongoing relief from symptoms, doctors often advise patients to take their medication at the same time each day. If a dose is missed, however, the patient should take it as soon as possible.

If it is almost time for the next dose of Theophylline and Guaifenesin, however, the patient should skip the dose completely. Patients should never take a double dose of the medication, unless they are advised to do so by a medical professional.

Patients can seek help from their physician or pharmacist if they have missed a dose of Theophylline and Guaifenesin and are unsure how to proceed.

Potential Drug Interactions

When taking any type of medicine, it's important to remember that the active ingredient(s) could interact with other medications, foods, vitamins and herbal supplements. In the case of combination medications, each active ingredient could potentially interact with other substances the patient consumes.

Patients taking Amifampridine and/or Riociguat, for example, will not normally be prescribed Theophylline and Guaifenesin as the medications may interact with each other.

Similarly, taking Theophylline and Guaifenesin with the following medications is not usually recommended:

  • Adenosine
  • Ceritinib
  • Bupropion
  • Blinatumomab
  • Halothane
  • Dienogest
  • Deferasirox
  • Desogestrel
  • Ciprofloxacin
  • Golimumab
  • Enoxacin
  • Drospirenone
  • Mexiletine
  • Erythromycin
  • Pefloxacin
  • Estradiol Valerate
  • Ethinyl Estradiol
  • Levofloxacin
  • Etintidine
  • Etonogestrel
  • Norgestrel
  • Fluvoxamine
  • Fosphenytoin
  • Dihydroartemisinin
  • Cimetidine
  • Idelalisib
  • Idrocilamide
  • Norgestimate
  • Ethynodiol Diacetate
  • Levonorgestrel
  • Medroxyprogesterone Acetate
  • Phenytoin
  • Donepezil
  • Norelgestromin
  • Rofecoxib
  • Imipenem
  • Fluconazole
  • Estradiol Cypionate
  • Peginterferon Alfa-2a
  • Peginterferon Alfa-2b
  • Mestranol
  • Pixantrone
  • Vemurafenib
  • Norethindrone
  • Secukinumab
  • Zileuton
  • Thiabendazole
  • Troleandomycin
  • Regadenoson
  • Siltuximab

If physicians deem it appropriate to prescribe Theophylline and Guaifenesin in conjunction with any of the medicines listed above, they may alter the dosage strategy in order to reduce the risk of interactions occurring.

While Theophylline and Guaifenesin can be prescribed with the following medications, the risk of side-effects occurring may increase:

  • Adinazolam
  • Alprazolam
  • Diazepam
  • Amiodarone
  • Halazepam
  • Brotizolam
  • Lorazepam
  • Carbamazepine
  • Ketazolam
  • Clobazam
  • Febuxostat
  • Clorazepate
  • Aminoglutethimide
  • Disulfiram
  • Estazolam
  • Clonazepam
  • Flunitrazepam
  • Flurazepam
  • Azithromycin
  • Interferon Alfa-2a
  • Medazepam
  • Isoproterenol
  • Chlordiazepoxide
  • Cannabis
  • Lormetazepam
  • Ipriflavone
  • Methotrexate
  • Secobarbital
  • Nilutamide
  • St John's Wort
  • Oxazepam
  • Ritonavir
  • Pentoxifylline
  • Tacrine
  • Piperine
  • Rifapentine
  • Propafenone
  • Quazepam
  • Rifampin
  • Prazepam
  • Riluzole
  • Pancuronium
  • Midazolam
  • Nitrazepam
  • Phenobarbital
  • Viloxazine
  • Temazepam
  • Zafirlukast
  • Triazolam
  • Telithromycin
  • Ticlopidine

As side effects may increase when taking Theophylline and Guaifenesin in conjunction with the drugs listed above, patients should receive further instructions from their physician. Often, taking the medications at certain times will relieve side effects. Patients should seek medical advice before altering their treatment regime, however. Alternatively, physicians may be able to prescribe additional medication to limit the side effects.

Taking Theophylline and Guaifenesin and smoking tobacco or consuming caffeine is not normally recommended. Similarly, the medication should not normally be taken with food. If the patient smokes or regularly consumes caffeine, they should discuss this with their physician prior to taking Theophylline and Guaifenesin.

Although medications can interact with one another, this doesn't mean that they necessarily will. In some instances, an interaction may simply mean that the dose needs to be modified. It is important, however, that patients inform their physician if they are taking any other medication, vitamins or supplements when they are prescribed Theophylline and Guaifenesin or any other medicine.


While Theophylline and Guaifenesin is an effective form of treatment for many people, it may not be suitable for every patient. Heart disease, convulsions, liver disease and underactive thyroid can be contra-indicators for treatment with Theophylline and Guaifenesin.

If patients have been diagnosed with any of these conditions, they should inform their physician before taking this medication. While some patients with the aforementioned conditions may not be able to take Theophylline and Guaifenesin, some may be able to proceed with treatment.

Taking Theophylline and Guaifenesin with an underactive thyroid may increase the effect of Theophylline, for example. By altering the dose accordingly, patients may still be able to take this medication, despite having an underactive thyroid.

When receiving Theophylline and Guaifenesin combination medication, patients should undergo regular monitoring and check-ups. Blood tests can indicate whether the dose should be changed and are, therefore, a necessary part of the treatment regime. Blood tests may need to be taken more frequently at the start of treatment, so that an appropriate dose can be established.

If the patient changes their routine or becomes unwell, the effects of Theophylline and Guaifenesin may change. If the patient experiences a fever of over 102ºF for 24 hours or a fever of over 100ºF for over 24 hours, they should consult their doctor. Similarly, if patients start or stop smoking, change their diet or start or discontinue another medication, the effects of Theophylline and Guaifenesin may change. Due to this, patients should consult their physician before making any major lifestyle changes when taking this medication.

Currently, there is limited research into the effect of Theophylline and Guaifenesin on pregnant women. Due to this, physicians may not prescribe this medication to patients who are pregnant, unless the benefits clearly outweigh any risks associated with the treatment. If a patient becomes pregnant when taking Theophylline and Guaifenesin or if a patient becomes pregnant soon after taking this medication, they should contact their physician for further advice.

Similarly, Theophylline and Guaifenesin may not be prescribed to women who are breastfeeding or nursing. Whilst Theophylline is not expected to cause any harm to infants if it is taken by a breastfeeding patient, there is limited data regarding the effects of Guaifenesin when taken by a breastfeeding patient. Physicians may, therefore, be unwilling to prescribe the medication to patients who are currently breastfeeding.

As with all medications, there is the possibility that Theophylline and Guaifenesin could cause an allergic reaction in some patients. Prior to taking the medication, patients should check the ingredients label to ensure that the medication does not contain any substances to which they are allergic.

An allergic reaction may be displayed as, difficulty breathing, facial swelling, swelling of the throat and/or lips, hives and/or collapse. As allergic reactions can pose a threat to life, this type of reaction requires urgent medical assistance.

If patients suspect they are suffering an allergic reaction to the medication, they should call 911 or seek emergency medical help from their nearest healthcare provider. If an overdose of Theophylline and Guaifenesin is suspect, the patient should obtain urgent medical care or contact a Poison Control Center on 1-800-222-1222.


When taking Theophylline and Guaifenesin orally, patients are advised to keep their medication at home, in a secure location. It is important to restrict access to medications in the home, particularly if children and/or pets are present. Using a lockable medicine cabinet or a locked storage box can be an ideal way to ensure that medications are kept secure.

In addition to this, Theophylline and Guaifenesin should be kept at room temperature and should not be frozen or heated. Patients should store the medication in a location which is shielded from direct sunlight, heat and/or moisture. This means that kitchens and bathrooms may not be the ideal place to store the medication.

If the medication reaches its use-by date, it should be disposed of. Similarly, if patients are advised to stop taking Theophylline and Guaifenesin, they should dispose of the medication responsibly. Medications should not be thrown away with general household waste as they could present a risk to anyone who has access to them. In most instances, pharmacies can provide advice or assistance when it comes to disposing of medications.


Any condition which causes respiratory issues can be extremely distressing for the patient. Asthma, chronic bronchitis and emphysema can be effectively managed by Theophylline and Guaifenesin combination medication and patients can experience relief from symptoms when taking this medicine.

Furthermore, Theophylline and Guaifenesin combination medicine can be used as a preventative measure in patients with asthma. If their condition presents on-going symptoms, the medicine should reduce instances of acute asthma attacks, as well as reducing the presence of low-level symptoms.

When treating asthma, chronic bronchitis, emphysema and other respiratory conditions, Theophylline and Guaifenesin can be used as individual medications. Whilst this may be an appropriate treatment option for some patients, using both active ingredients can provide a more effective solution for patients.

By relaxing the relevant muscles and increasing air flow, Theophylline should enable patients to breathe more easily; whilst the addition of Guaifenesin should reduce congestion and ensure that the patient's breathing is not made worse by the presence of mucus.

Due to the efficacy of both medications in treating respiratory conditions, prescribing Theophylline and Guaifenesin as a combination medication is often advantageous. As well as providing patients with effective treatment, this combination medication reduces the need for patients to take additional tablets, capsules and/or syrups each day.

In addition to this, the dose of Theophylline and Guaifenesin can be altered, even when it is taken as a combination medication. As a result, prescribing a combination of Theophylline and Guaifenesin ensures that patients benefit from a consistent dose of both active ingredients and that they have on-going access to a convenient treatment regime.

Last Reviewed:
December 25, 2017
Last Updated:
April 05, 2018
Content Source: