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Drug Interactions between phentermine / topiramate and Synthroid

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

levothyroxine phentermine

Applies to: Synthroid (levothyroxine) and phentermine / topiramate

Talk to your doctor before using levothyroxine together with phentermine. Combining these medications may increase the risk of cardiovascular side effects such as high blood pressure, palpitation, chest pain, and irregular heart beat. If you have preexisting heart disease, your condition may worsen. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Moderate

phentermine topiramate

Applies to: phentermine / topiramate and phentermine / topiramate

Topiramate may increase the blood levels and effects of phentermine. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Contact your doctor if you experience increased side effects such as dizziness, restlessness, insomnia, tremor, headache, mood changes, palpitation, rapid heart beat, or blood pressure elevation. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Drug and food interactions

Moderate

levothyroxine food

Applies to: Synthroid (levothyroxine)

The timing of meals relative to your oral levothyroxine dose can affect the absorption of the medication. Therefore, levothyroxine should be taken on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in blood levels, which may alter its effects. In addition, absorption of levothyroxine may be decreased and/or delayed by foods such as soybean flour, cotton seed meal, walnuts, dietary fiber, calcium, calcium fortified juices and grapefruit or grapefruit juice. These foods should be avoided within several hours of dosing if possible. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Moderate

phentermine food

Applies to: phentermine / topiramate

Using phentermine with alcohol can increase the risk of cardiovascular side effects such as increased heart rate, chest pain, or blood pressure changes. In addition, you may also be more likely to experience nervous system side effects such as dizziness, drowsiness, depression, and difficulty concentrating. You should avoid or limit the use of alcohol while being treated with phentermine. Do not use more than the recommended dose of phentermine, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medication without first talking to your doctor.

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Moderate

levothyroxine food

Applies to: Synthroid (levothyroxine)

Using multivitamin with minerals together with levothyroxine may decrease the effects of levothyroxine. You should separate the administration of levothyroxine and multivitamin with minerals by at least 4 hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.


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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.