Hemicrania continua is a type of primary headache that causes continuous pain on one side of the head for prolonged periods.

Hemicrania continua is a primary headache, which means no other condition or disease causes it to occur. In most cases, the pain remains continuous for over a month and is punctuated by periods of severe pain.

There are two types of hemicrania: chronic and remitting. Chronic hemicrania involves having daily headaches that occur indefinitely. Remitting hemicrania refers to persistent headaches that may last up to 6 months, followed by periods without symptoms.

The following article discusses hemicrania continua’s causes, symptoms, treatment, and outlook.

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According to the National Institute of Neurological Disorders and Stroke, the exact cause of the hemicrania continua is unknown.

The organization states that two factors — alcohol consumption and physical exertion — may lead to worsening pain in some people living with the condition. However, the Migraine Trust notes that the condition’s triggers are unclear.

Potential risk factors

As with triggers for the condition, medical experts know little about the risk factors for developing hemicrania continua.

The Genetic and Rare Diseases Information Center notes that biological females are more likely to develop hemicrania continua than biological males. Doctors typically diagnose the condition in adults, but it can start any time between the ages of 5 and 67 years.

Hemicrania continua treatment focuses on prevention. There is no known cure for the condition.

The most effective form of treatment is indomethacin, a type of nonsteroidal anti-inflammatory drug (NSAID). For indomethacin to work effectively, a person must take 25–300 milligrams daily for an indefinite period to relieve symptoms.

In proper doses, indomethacin is so effective that doctors may even use it to diagnose the condition. In other words, a headache that does not respond to indomethacin is likely not hemicrania continua.

Not everyone can tolerate taking indomethacin. For mild side effects, a doctor may prescribe acid-suppression medicine to help reduce gastrointestinal complications.

A doctor may also prescribe celecoxib, another form of NSAID that has fewer side effects.

Finally, a doctor may prescribe amitriptyline or another tricyclic antidepressant to help prevent headache pain.

The most obvious and common symptom of hemicrania continua is a dull, continuous headache on one side of the head that lasts for days or weeks, sometimes even longer. However, some people may experience pain on both sides of the head.

In addition, a person will experience occasional throbbing pain on the same side of the head as the dull ache.

To receive a diagnosis of hemicrania continua, a person must also experience at least one of the following symptoms:

  • eye redness or tearing
  • miosis (contracture of the iris)
  • nasal congestion
  • ptosis (drooping eyelid)
  • runny nose
  • restlessness or pain aggravated by movement

Some people may also experience forehead sweating and migraine-like symptoms, such as:

  • vomiting
  • throbbing pain
  • light and sound sensitivity
  • nausea

The International Headache Society provides clear criteria for diagnosing hemicrania continua.

In addition to having pain on only one side of the head, a person must also have:

  • an ongoing, dull headache for 3 or more months
  • a headache that gets better with therapeutic doses of indomethacin
  • at least one additional symptom, including runny nose, ptosis, nasal congestion, restlessness, miosis, or redness or tearing in the eye

Also, the headache and symptoms must not fit the criteria for, or be better explained by, any other type of headache.

A doctor cannot diagnose hemicrania continua without a person having a demonstrated history of continuous pain for at least 3 months.

If the pain is dull and one-sided, a person should consider keeping a headache journal and contact their doctor when they reach or approach the 3-month mark.

However, a person should see their doctor as soon as possible if they have a severe headache accompanied by fever or other concerning symptoms. In certain cases, a severe headache can be a symptom of a more serious health condition that requires immediate medical attention.

Once a person receives a diagnosis of hemicrania continua, they may want to consider continuing the headache journal. This can help them determine if their treatment regimen is working.

A person should also consider talking with their doctor about possible alternative treatment options if they experience side effects from the medication.

Hemicrania continua has no cure, but a person can prevent pain from returning through continual preventative medication use.

Some people may experience side effects from taking indomethacin. If side effects occur, a person should talk with their doctor about other possible treatment options that may be effective in preventing headache pain.

Hemicrania continua is an ongoing headache that affects one side of the head and can cause occasional severe headaches.

The most effective treatment is indomethacin, which is a type of NSAID.

A person will need to take a consistent dose of the medication indefinitely to prevent the pain from occurring.

If a person cannot tolerate the main course of treatment, they should talk with their doctor about alternative medications to help prevent the pain from returning.