Can I Use Medifast If I'm On Prescription Medications? What If I Get Sick?

First, make sure your physician is consulted prior to and while you are on the Medifast. Generally, most prescription drugs for chronic conditions such as thyroid, depression or hormone deficiency, etc. will not interfere with the Medifast Plan. However, the dosages may need to be adjusted because the plan can improve blood sugar, blood pressure, and cholesterol levels.


Can I Use Medifast If I'm On Prescription Medications? What If I Get Sick?

If you are currently taking a diuretic, you need to ask your physician whether a low calorie diet is appropriate for you.

Unless absolutely necessary, avoid taking diuretics while you are on Medifast because it may result in an alteration of your sodium/potassium levels due to increased urine output.

If you have taken a diuretic while you are on Medifast, check with your physician and the physician may wish to monitor your electrolytes and adjust the dosage of diuretic. You may need wean off the medication slowly rather than stopping it abruptly.

Oral Diabetes Medication & Insulin

Medifast Plus for Diabetics can help Type II diabetes control blood sugar and lose unwanted pounds, but it is not recommended for people with Type I diabetes. You must see your physician before starting the Medifast to discuss blood sugar monitoring, potassium monitoring, diabetes pills, calorie levels.

While on the Medifast, you need to monitor your blood sugar readings once or twice a day as well as stay in close contact with your physician, some diabetics may need to reduce the use of diabetes medications. If your insulin dose is less than 30 units a day, Medifast recommends you discontinue it entirely when you begin the plan. If you are on more than 30 units a day, you can usually decrease your dose by half, then reduce it further as your blood-sugar level drops.

Blood Pressure Medications

If you are taking blood-pressure medication, consult to your physician. You may be able to decrease the dose or eliminate taking it, at least during the time you are on Medifast. Watch for any of these symptoms that can indicate your medication dose needs to be lowered or discontinued :

Feeling tired, Weak or "Washed Out"
Legs feeling rubbery or weak
Feeling dizzy or Light-headed
Becoming more fatigued after several weeks of feeling great

Thyroid Medication

Individuals with hypothyroidism can use Medifast under the direct supervision of a physician. But your physician may suggest using a soy-free Medifast product around the time of day that you take thyroid medication. The weight will come off, but it may not come off as fast as someone that does not have a thyroid problem.


We do not recommend using Medifast if you are using over 20 mg of steroids (such as Cortisone or Prednisone) per day, since these medications may prevent weight loss.

Cold or Flu

If you become ill with a cold or the flu, you can stay on the 5 & 1 Plan provided your symptoms are not too severe. Taking antibiotics (prescribed by your doctor) won't harm your Medifast plan but may temporarily slow your weight loss.