Why Do You Have a Headache & Diarrhea?

Key takeaways:

• Headaches and diarrhea often have treatable, non-life-threatening causes, but persistent symptoms should be evaluated by a doctor.
• Dehydration from diarrhea can worsen headaches, so staying hydrated is crucial.
• Headaches and diarrhea may signal infections, pregnancy, or other conditions—consult your doctor if symptoms last more than 48 hours.

Headache and diarrhea are concerning symptoms that often leave patients with questions. While it’s common to worry these symptoms might indicate a serious illness, many causes are treatable and not life-threatening.

However, these symptoms can disrupt daily life and productivity, making it important to monitor them closely. You can observe your symptoms at home for 48 hours, but if they persist or worsen, you should call your doctor. Although it may not seem obvious how these two symptoms are connected, certain conditions can cause them to occur together.

Are headaches and diarrhea related?

Headaches and diarrhea can happen together. Several conditions lead to these two symptoms. In some instances, such as migraines, the diarrhea leads to the headache.

Common causes of headache and diarrhea experienced together

There are several causes of headache and diarrhea. Knowing the signs and symptoms of each can help determine the cause.

Infection

Viral infections such as gastroenteritis, influenza, or COVID-19 can cause headaches and diarrhea. You may also experience other symptoms such as fever, chills, runny nose, muscle aches, abdominal pain, nausea, and vomiting. It depends on the exact cause of your illness. Dehydration, whether from diarrhea or another cause, can lead to headaches. Dehydration can also make an existing headache feel worse.

Migraine

A migraine headache is usually a severe, one-sided headache. It is often accompanied by light sensitivity and nausea. Attacks or episodes can last for hours to days. New research suggests diarrhea can be a symptom of migraines. Additionally, dehydration can trigger a migraine episode. If you are dehydrated from diarrhea, this may lead to a migraine headache.

Pregnancy

Headache and diarrhea alike can occur during pregnancy. These can happen during any trimester and may have benign or serious causes. It is important to call your doctor if you are experiencing these symptoms and are pregnant or think you may be pregnant.

Read our guides on different types of diarrhea and causes of diarrhea for more.

Causes of headaches and diarrhea based on another symptom, condition, or situation

If you are experiencing symptoms in addition to headaches and diarrhea, these may point towards the cause.

Headache, diarrhea, and fatigue

A viral infection such as influenza or COVID can explain these symptoms. Viruses can infect multiple organ systems and cause fatigue and headaches. Feeling fatigued if you suffer a migraine with diarrhea is also understandable. Pregnancy can explain these symptoms, too.

Headache, diarrhea, stomach pain, or nausea and vomiting

This can be explained by an infection, particularly viral gastroenteritis or influenza. Migraines can lead to headache and nausea, with abdominal pain and diarrhea being less common (but not impossible). Pregnancy is another possibility explaining these findings.

Headache, diarrhea, and fever/chills

This pattern of symptoms would be most worrisome for an infectious cause. Influenza, COVID-19, or a gastroenteritis virus explains these symptoms. Also, remember that dehydration from any cause can lead to a headache.

Headache, diarrhea, and sore throat

These symptoms together raise suspicion of an infection such as influenza or COVID-19. Any virus infecting the throat can move into the GI tract and cause diarrhea. Headache in this scenario can be caused by the virus itself or by dehydration caused by the symptoms.

Headache, diarrhea, and a stiff neck

Certain groups of viruses can cause viral meningitis. Meningitis is an infection of the fluid and membranes surrounding the brain and spinal cord. The classic symptoms of meningitis include fever, headache, light sensitivity, and neck stiffness. Projectile vomiting can also be present.

The same viruses that lead to meningitis can also cause GI upset, vomiting, and diarrhea. If you suspect you have meningitis, seek emergency medical care.

Headache and diarrhea while pregnant

The cause of headache and diarrhea during pregnancy depends on which trimester you are in. The list of causes ranges from benign to serious. Call your doctor if you are pregnant and have a headache and diarrhea.

Treatment options for headaches and diarrhea

Treatment for headache and diarrhea is often directed at the symptoms.

Rehydration

Rehydration is one of the mainstays of treatment for diarrhea. The best way to rehydrate is to drink an oral rehydration solution or a low-sugar sports drink. You can purchase oral rehydration packets or drinks at your local pharmacy. You can make a rehydration solution at home if you’d prefer.

Over-the-counter medication

Several potential over-the-counter therapies can help your symptoms. Probiotics restore normal intestinal bacteria destroyed by diarrhea. These can reduce the length of your illness.

Anti-diarrheal agents are also useful for your symptoms. Speak to your doctor before starting these medications. These can make some infections worse and cause serious complications.

Some over-the-counter medications are helpful for a headache. Paracetamol and ibuprofen are safe for most patients. Avoid ibuprofen if you are pregnant, have stomach ulcers, or have kidney disease.

If you think you are experiencing a migraine, follow your doctor’s migraine plan.

When to see a doctor about headaches and diarrhea

If the diarrhea and headache start to improve within 48 hours, you probably don’t need to see a doctor. However, if the symptoms worsen or new symptoms develop, call your doctor.

You should see a doctor if:

• The diarrhea lasts longer than 48 hours.
• The symptoms are so severe you cannot complete normal daily tasks.
• You have a fever (temperature greater than 100.4 degrees Fahrenheit).
• You notice bloody or dark-black (tarry) stools.
• There are signs of dehydration.
• If you have recently taken antibiotics and now have diarrhea.

You should go to the emergency room if:

• You are experiencing severe abdominal pain.
• You have not made any urine for 6 hours.
• The patient is confused or having difficulty staying awake.
• You have a stiff neck and/or projectile vomiting.

Questions to ask your doctor about headaches and diarrhea

• What do you think is causing these symptoms?
• Can I take over-the-counter medications for the symptoms?
• How long do you expect this to last?
• When should I call you back if I don’t think I’m improving?

Frequently asked questions: headaches and diarrhea

It is normal to have questions about your symptoms. You should ask your doctor any questions you have. While diarrhea can be an embarrassing subject, your doctor wants to help you feel better.

What viruses cause a headache and diarrhea?

While many viruses can cause these symptoms, among the most common are influenza and COVID-19. And remember that dehydration for any reason can cause a headache.

What if you’ve experienced headaches and diarrhea for a week?

If you have experienced headaches and diarrhea for a week, call your doctor.

Are headaches and diarrhea a sign of COVID?

They can be, though this is not the only potential cause of headaches and diarrhea.

Closing thoughts

There are multiple causes of headaches and diarrhea. Thankfully, most are not life-threatening. Speak to your doctor if you are unsure what may be causing your symptoms.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Pallabi Sanyal-Dey, MD.

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