Headache pain can range from mild to severe and can last for hours or even days. There are numerous potential causes, including migraine, a head injury, or a viral illness, such as COVID-19.

Anyone who has a headache for days that does not respond to over-the-counter (OTC) pain relief medication should seek guidance from a doctor.

In this article, we discuss the potential causes of a headache lasting for days. We also look at how healthcare professionals diagnose and treat it.

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A headache is a common symptom of COVID-19, and some people continue to experience headaches for weeks after the initial SARS-CoV-2 infection. These headaches may occur frequently, even daily.

A 2020 study found that out of 130 participants with COVID-19, 74.6% had mild to moderate headaches. Just under one-quarter of the participants experienced severe, migraine-like headaches. The pain often began at the same time as other COVID-19 symptoms. It can also be the earliest symptom to appear.

Researchers are still trying to understand how SARS-CoV-2 affects the body and why some people develop persistent symptoms, which health experts refer to collectively as long COVID.

These symptoms may be related to the trigeminovascular system, which includes a nerve that starts at the ear and radiates to the brows, nose, and jaw. Inflammation of this nerve may be the reason some individuals develop persistent headaches and other COVID-19 symptoms, such as loss of taste or smell.

Find a list of all potential COVID-19 symptoms here.

Migraine is a neurological condition that causes episodes of moderate to severe headache along with other symptoms. These can include:

Often, migraine pain occurs on one side of the head. The headache phase can last up to 72 hours before improving, but occasionally, people can have status migrainosus. This is a migraine attack that lasts more than 72 hours and does not improve with standard treatment.

A doctor can diagnose migraine and recommend the best treatment options. These may include OTC pain relief medications or prescription medications for migraine.

If a person has status migrainosus, doctors may recommend:

The sinuses are small air pockets inside the face. If they become blocked or inflamed, people can develop sinus headaches, or sinusitis, which may last for days.

A sinus headache usually causes tenderness and constant pain in the affected sinus. The pain is typically a deep, dull ache that worsens when a person moves their head. The person may also have:

Sinusitis can result from allergies, an infection, or coming into contact with irritants. Doctors can help treat these with medications.

For symptom relief, individuals can use pain relief medication or nasal vasoconstrictors, which are substances that narrow blood vessels to reduce pain.

Head injuries can cause persistent headaches that either worsen or do not get better over time.

Head injuries can lead to concussion or a traumatic brain injury (TBI), which requires immediate medical attention.

An individual will usually experience a TBI after sustaining a penetrating or blunt force injury to the head, which can occur due to falls, sports injuries, accidents, or assault.

In addition to a headache, symptoms of a TBI may include:

A person should dial 911 or the number of their nearest emergency department if they or someone else has experienced a head injury or has TBI symptoms. A person should do this even if the symptoms do not develop immediately after the injury.

Many other conditions and factors might lead to persistent or daily headaches, including:

Doctors usually start diagnosing the cause of a persistent headache by asking a person about the pain. They may ask:

  • when the headache began
  • where the pain occurs and how it feels
  • what medications the person is taking
  • whether the person has any additional symptoms
  • whether the headaches occur at a certain time or after a certain activity
  • whether the person has a family history of headache or neurological conditions, such as migraine

The doctor may perform a physical examination to check for signs of infection and to rule out other conditions. They may also order tests such as an MRI scan or a CT scan.

Anyone with a headache that lasts for at least 3 days and does not respond to OTC treatments should contact a doctor. This is especially true if the headache:

  • is a new or unusual symptom, particularly in people aged over 50 years
  • significantly changes in intensity when a person changes position, such as when they go from lying down to standing up
  • starts when a person coughs, sneezes, or strains
  • occurs alongside unexplained weight loss or night sweats
  • does not respond to OTC drugs or a person’s usual migraine medication

If COVID-19 is a possibility, it is safer to contact a doctor over the phone, unless otherwise instructed by a healthcare professional. A person should stay at home and follow the local health authority’s instructions for getting tested.

Some headache symptoms can indicate a medical emergency. Seek immediate help if you or someone else experiences:

  • a head injury
  • a thunderclap headache, which starts suddenly and reaches peak intensity in minutes
  • a headache that is more painful than any headache ever before
  • sudden weakness on one side of the body, difficulty walking, or difficulty raising the arms
  • changes to levels of consciousness, such as fainting
  • a headache along with a stiff neck or a rash that does not disappear under a glass
  • seizures

There are various potential causes of a persistent headache. Some causes, such as migraine, typically do not require urgent medical attention. Other causes, however, such as a TBI, are medical emergencies.

Having a headache for days can also be a symptom of COVID-19 or long COVID. Researchers have recorded headaches that persist for more than 6 weeks after a SARS-CoV-2 infection.

Since there are many causes for headaches, it is important to seek medical advice as soon as possible instead of trying to self-diagnose.