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Synthroid (levothyroxine) is a synthetic form of thyroxine, a hormone naturally produced by the thyroid. The medication is used when the thyroid is unable to produce sufficient quantities of the hormone due to injury, medications or abnormalities. This condition of insufficient hormone production is commonly called hypothyroidism or underactive thyroid.

The medication is also used to treat goiter in some situations, and may prevent the need for surgery.

Managing Hypothyroidism

Synthroid replaces the hormone thyroxine in the body; it does not improve thyroid function in any way. While other measures may be taken to resolve the underlying thyroid issue, Synthroid provides relief from the often unpleasant and sometimes dangerous symptoms of an underactive thyroid in the interim:

• Chronic fatigue
• Thinning hair
• Memory loss
• Increased cold sensitivity
• Weight gain
• Weakness
• Muscle or joint aches
• Increased cholesterol
• Decreased heart rate
• Excessively dry skin
• Chronic constipation
• Hoarseness
• Puffiness in face

As the above symptoms may have many causes that do not involve an underactive thyroid, the condition should be diagnosed before initiating treatment with Synthroid. Too much thyroxine can be every bit as dangerous as too little.

In otherwise healthy adults who have been diagnosed with hypothyroidism, treatment is roughly as follows:

• Take 1.7 mcg of levothyroxine per kg of weight per day.
• Daily doses are taken once per day on an empty stomach, typically in the morning 30 to 60 minutes before consuming anything other than water.
• You may need to wait up to 4 hours before consuming certain foods, vitamins, supplements, or other medications.
• Improvements are usually noticed within 4 to 6 weeks of initiating Synthroid therapy, but it may take several months for full effects to be felt.
• Treatment should continue for as long as needed, which may be for the remainder of life.
• If treatment is stopped symptoms of hypothyroidism may reappear.

There are many factors which may influence treatment, including the severity of the hypothyroidism, age, weight, other medications being taken, and so forth. Ideally there should be regular doctor exams throughout treatment to make dosage adjustments if needed.

Warnings and Side Effects

There are a wide range of foods, vitamins, supplements and other medications, including non-prescription, which may interfere with Synthroid. Some interactions can produce dangerous side effects, while others may reduce the effectiveness of one of the medications involved. If in doubt, ask a doctor or pharmacist, or wait at least 4 hours after taking Synthroid before consuming the product in question. A very short list of potential Synthroid interactions includes:

• Grapefruit
• Coffee
• Calcium
• Iron
• Antacids
• Amphetamines
• Lithium
• Steroids
• Insulin
• Blood thinners

Most side effects associated with Synthroid are mild and stop occurring within the first month of treatment:

• Headache
• Nausea
• Diarrhea
• Stomach cramps
• Difficulty sleeping
• Restlessness
• Temporary hair loss
• Sweating
• Mild mood swings
• Increased appetite
• Weight loss

The above side effects are not cause for concern unless severe or persistent beyond one month of treatment.

Rarely more dangerous side effects may develop, particularly if dosage is too high. It may take a week to 10 days after a dosage change for adverse effects to be noticeable, so patients should be alert for:

• Abnormal heart beat
• Severe abdominal pain
• Extreme confusion or agitation
• High fever
• Seizures
• Unconsciousness

If the above symptoms are noticed emergency medical attention should be sought.

As one of Synthroid's side effects is weight loss, there has been some interest in the product as a weight-loss aid. While it is true many patients experience weight loss as thyroxine levels return to normal, the medication does very little to promote weight loss if hypothyroidism is not present. Using this product in quantities large enough to produce appreciable weight loss when the thyroid is functioning normally is extremely dangerous and may prove fatal.