To treat hypothyroidism, your doctor will prescribe the synthetic thyroid hormone, levothyroxine. This medicine increases your thyroid hormone levels to relieve symptoms like fatigue, cold sensitivity, and weight gain.

To get the most from your thyroid medicine, you need to take it correctly. One way to do that is to ask your doctor a lot of questions every time you get a new prescription.

Your pharmacist is another good resource on drug dosing and safety. But don’t expect the pharmacist to offer up a thorough explanation of your medicine and how to take it when you drop off your prescription. You’ll need to start the discussion.

Here are a few questions to ask your pharmacist before you start on your thyroid hormone drug or get on a new dose.

A few different versions of levothyroxine are available. They include:

  • Levothroid
  • Levo-T
  • Levoxyl
  • Synthroid
  • Tirosint
  • Unithroid
  • Unithroid Direct

You can buy generic versions of these drugs, too. All levothyroxine products contain the same type of thyroid hormone, T4, but the inactive ingredients can differ between brands. Switching brands could affect the effectiveness of your treatment. Let your pharmacist know that you want to be alerted of any changes to your prescription.

Ask how many pills to take, when to take them (morning, afternoon, or evening), and whether to take them on an empty or full stomach. You’ll usually take thyroid hormone in the morning with a full glass of water on an empty stomach to maximize absorption.

It’s very important to get the thyroid hormone dosage right. Your doctor will carefully adjust your dose based on blood tests. Make sure the dose written on the bottle label is what your doctor prescribed. Taking too much thyroid hormone can cause side effects like shaking and heart palpitations.

Your pharmacist might tell you to take the medicine again as soon as you remember. If your next scheduled dose is coming up, you should skip the dose you missed and resume your medication on your regular schedule. Don’t double up on the dosage.

Your pharmacist should have a record of all the other medicines you take. Go over this list and make sure none of the drugs you take can interact with your thyroid hormone. Interactions can cause side effects, and possibly make your thyroid drug less effective.

Prescription medicines that can interact with levothyroxine include:

  • antiseizure drugs, such as phenytoin (Dilantin),
    carbamazepine (Tegretol)
  • blood thinners, such as warfarin (Coumadin)
  • birth control pills
  • cholesterol-lowering medicines, such as colesevelam
    (Welchol),
    cholestyramine (Locholest, Questran)
  • estrogen derivatives
  • fluoroquinolone antibiotics, such as
    ciprofloxacin (Cipro), levofloxacin
    (Levaquin), lomefloxacin (Maxaquin), moxifloxacin
    (Avelox), ofloxacin (Floxin)
  • rifampin (Rifadin)
  • selective estrogen receptor modulators, such as
    raloxifene (Evista)
  • selective serotonin reuptake inhibitor
    antidepressants, such as sertraline (Zoloft),
    theophylline (Theo-Dur)
  • sucralfate (Carafate)
  • tricyclic antidepressants, such as amitriptyline
    (Elavil)

Tell your pharmacist about every supplement and medicine you take — even ones you buy without a prescription. Some supplements and over-the-counter medicines can cause side effects when you take them with your thyroid hormone. Others can prevent your body from properly absorbing levothyroxine.

Supplements and over-the-counter drugs that can interact with levothyroxine include:

  • calcium and other antacids (Tums, Rolaids,
    Amphojel)
  • gas relievers (Phazyme, Gas-X)
  • iron
  • weight loss medicines (Alli, Xenical)

Go over your diet with your pharmacist. Certain foods can make your thyroid medicine less effective. These include grapefruit juice, soy foods such as tofu and soybeans, espresso coffee, and walnuts.

Go over the list of side effects on the drug’s information sheet with your pharmacist. The most common side effects from levothyroxine are:

  • nausea, vomiting
  • diarrhea
  • stomach cramps
  • weight loss
  • shaking
  • headache
  • nervousness
  • trouble sleeping
  • sweating a lot
  • increased appetite
  • fever
  • changes in menstrual period
  • increased sensitivity to heat
  • temporary hair loss

Just because a side effect is on the list doesn’t mean you’ll experience it. Ask your pharmacist which side effects they see most often, and what factors make you more likely to develop certain side effects.

Find out which side effects warrant a call to your doctor. Some of the more serious side effects from thyroid hormone include:

  • chest pain or tightness
  • fainting
  • fast or uneven heartbeat
  • severe fatigue
  • swelling of your lips, throat, tongue, or face
  • trouble breathing or swallowing

Your pharmacist will probably tell you to store levothyroxine at room temperature, in an area that doesn’t have a lot of moisture (avoid the bathroom). Keep the medicine in its original container, and out of children’s reach.

While you may assume that your doctor knows all the answers to your hypothyroidism treatment, your pharmacist can be just as helpful. Asking the right questions may make the difference between starting a medication that you rightly thought you were prescribed to getting on a generic brand.