Headaches: Cluster - Medications

Highlights	Risk Factors	Surgery
Introduction	Diagnosis	Resources
Cluster Headaches	Managing Cluster Headaches	References
Causes	Treatment
Prognosis	Medications

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Medications

Calcium-channel blockers, commonly used to treat heart disease, are important agents for preventing cluster headaches. Verapamil (Calan) is the standard calcium-channel blocker used for headache prevention. Constipation is a common side effect. No one taking any calcium-channel blocker should withdraw abruptly, because such action could dangerously increase blood pressure. Overdose can cause dangerously low blood pressure and slow heart beats. It should be noted that drinking grapefruit juice or eating grapefruit with these drugs could enhance their potency, sometimes to toxic levels that can cause heart failure in patients with heart disease.

Lithium

Lithium (Eskalith, Lithane, Lithobid, Lethonate, Lithotabs), commonly used for bipolar disorder, is beneficial for cluster headaches and is the most effective agent for chronic cluster patients. One small study suggested that lithium may act directly on the nerve clusters affecting the circadian rhythm and slow down the cycle of this "biologic clock." (There is some evidence that cluster headaches are caused by a failure in the biologic clock.) The patient usually experiences benefits within two weeks, and often within the first week. It is not clear how or why it works for cluster headache patients. Lithium may be used alone or with other drugs.

Toxic Effects. Minor toxic reactions include the following:

Trembling hands.
Nausea.
Increased urine output.
Some loss of coordination.

More severe reactions, which occur at higher blood levels, are the following:

Convulsions.
Uncontrolled jerky movements in arms and legs.
Blurred vision.
Vomiting.
Stupor.
Coma.

Very high blood levels of lithium can be fatal.

If toxicity occurs, drugs should be stopped immediately and one or more of the following steps taken, depending on severity:

Patients are given fluids and drugs to increase excretion of lithium salts.
Gastric lavage, a procedure that rinses the stomach may be used to treat very recent overdoses.
Hemodialysis, a procedure that filters lithium out of the blood, may also be performed in severe cases.

Long-Term Side Effects. Even for patients who do not experience a toxic response, long-term use of lithium is not without problems. Some patients may experience the following:

An unpleasant taste in the mouth.
Hair loss.
Weight gain. In one study 16% of patients gained weight. It is a frequent reason for noncompliance and for relapse.
Skin eruptions that can resemble acne. (It can worsen psoriasis in patients who also have this condition.)
Thyroid problems. Up to 20% of patients who take lithium develop symptomatic hypothyroidism, and another 20% to 30% develop hypothyroidism without symptoms.
An increased risk for diabetes.
A blunted sexual drive.
Dulled emotions and mental acuity.
Memory loss.
Lack of motor coordination.
An increased risk for diabetes associated with kidney impairment.
Reduced sensitivity to light. In some cases, this may slightly affect color recognition. More seriously it can cause problems with night driving. This effect occurs regardless of how long a person has been on the drug. Experts recommend that patients wear sunglasses outside and avoid extensive exposure to bright light.