SNOOP Criteria for Headache Red Flags or Warning Signs

The American Headache Society has a handy mnemonic device for remembering headache warning signs — reasons to call your healthcare provider right away. All you have to do is remember the mnemonic “SNOOP.”

Doctor speaking with patient
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S: Systemic Symptoms

This refers to any symptoms, in addition to your headache, that affect the body as a whole. Some systemic symptoms include fevers, muscle pain, and weight loss. This “S” can also refer to secondary risk factors, like HIV or cancer. For instance, if a person has cancer, a new headache could be a sign that cancer has spread to the brain.

N: Neurological Signs or Symptoms

Any headaches associated with changes in cognition, mental functioning, or personality or deficits in one or more areas of the body, like weakness or loss of sensation requires immediate medical attention. This could be an indication of a stroke, mass in the brain, or other vascular or autoimmune process in the nervous system.

O: Onset

Onset refers to how fast a headache sets in. Headaches that hit suddenly and severely, without warning, also called thunderclap headaches, can be a sign of a stroke, especially a bleed in the brain known as a subarachnoid hemorrhage. If straining, coughing, or sexual activity causes a headache to appear, you should also discuss this with your healthcare provider.

O: Older Age of Onset

If you are a bit older when you first start to experience headaches, you may actually have a more significant problem than simple migraines. This is especially true if you are age 50 or older — one type of headache that can newly develop in middle-aged people is giant cell arteritis.

P: Prior Headache History

Compare a current headache with headaches you have experienced in the past. If your headache pattern has changed, like become more severe in intensity, more frequent, or associated with new symptoms like fatigue, than please seek medical attention. Likewise, if you are experiencing the first or worst headache of your life, seek medical attention right away, as this could indicate bleeding within the brain.


SNOOP is a mnemonic for assessing headache warning signs and knowing when to call a healthcare provider immediately or seek emergency care. It stands for systemic symptoms, neurological signs, onset, older age at onset, and prior medical history.

Aside from being painful and annoying, headaches are often just that—headaches. They do not indicate that you absolutely have a more significant illness or condition. That being said, taking the time to assess your headaches using the SNOOP mnemonic can give you peace of mind and a more organized way to classify your headaches.

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By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.