Constipation Headaches – Causes of Difficulty with Stools and Head Pain

Constipation and headaches may seem like largely unrelated symptoms but sometimes both of these symptoms can occur together. This can be due to a variety of reasons. However, in most cases constipation does not cause headaches and vice versa as is sometimes incorrectly thought. In fact the headache and constipation that may occur simultaneously could be due to entirely different causes and are not related in any way.

Meaning of Constipation and Headaches

Constipation is a problem with passing stool. It is technically defined by having less than three bowel movements in a week with a difficulty in passing stool which is often hard. Most people with constipation need to strain to pass stool when possible. It is this straining that may at times contribute to headaches.

Headaches refers to pain in the head. There are many different types of headaches which are categorized according to the nature, duration, cause and location of the headache. Like constipation, headaches are a symptom of some underlying cause and at times this cause may be responsible for both symptoms – constipation and headaches.

However, it has to be stressed that it is unclear whether there is direct causation between headaches and constipation as is sometimes observed in some people. In some types of severe headaches, like migraines, the pain response can affect bowel activity. Therefore there may be constipation which exists while the pain is present but may subsequently ease when the migraine subsides. This can occur with any form of severe pain, and not only with headaches.

Read more on constant headaches.

Causes of Constipation and Headaches

Constipation and headaches may arise as a result of different mechanisms. Some of these mechanisms have been discussed below under the different causes. However, there many instances where the exact mechanism and cause of both constipation or a headache cannot be identified. There could possibly be a link between these two symptoms that is not as yet understood below the causes discussed below. Alternatively, both symptoms arise independently but may be present simultaneously in some people thereby leading to the belief that constipation causes headaches or vice versa.


Most people who are constipated have to strain to have a bowel movement. This straining may contribute to headaches. Excessive straining to pass stool may extend beyond the abdominal muscles and a person may also tightly contract the neck, head and face muscles during this time. Spasm of these muscles can cause headaches. Furthermore straining can increase blood pressure which may then contribute to headaches as well.


Dehydration is a common cause of both constipation and headaches. Hard and dry stools that are characteristic of constipation may arise with insufficient water intake. Similarly insufficient fluid and electrolyte levels may lead to muscle spasm that can lead to headaches. This is more pronounced with moderate to severe dehydration. However, even in mild dehydration a person may experience some of these symptoms.


Insufficient food intake can result in constipation, especially when the minimal food that is being consumed is low in appetite. Furthermore the inadequate food intake may also result in low blood glucose levels (hypoglycemia) which can then contribute to headaches. Starvation does not only apply to the inability to access food due to inadequate availability of food and financial resources. Even strict dieting and prolonged fasting may have a similar effect. In addition, dehydration may also occur in these individuals, further contributing to both headaches and constipation.

Pregnancy and PMS

The change in hormone levels that may occur in pregnancy, premenstrual syndrome (PMS) and menopause can contribute to headaches and constipation. Pregnant women are particularly prone to both of these symptoms for several reasons beyond the hormonal fluctuations. Severe morning sickness and a loss of appetite can lead contribute to headaches in the same way as dehydration and starvation. In late pregnancy, the enlarged uterus may also press against the bowels while changes in blood pressure can lead to constipation and headaches, respectively.


Fibromyalgia is a disorder where there is muscle pain at various parts of the body and it is often accompanied by fatigue, sleep problems and mood disorders. Most people with fibromyalgia also experience headaches. Constipation is another symptoms that may occur and is often associated with irritable bowel syndrome IBS, which is a common condition to accompany fibromyalgia.

Read more on signs of fibromyalgia.

Celiac Disease

Celiac disease is an immune-mediated reaction whereby the body’s immune system reacts to the presence of gluten, a protein found in wheat. This causes inflammation of the bowels which further prevents other nutrients from being absorbed from the gut. Although diarrhea is a more likely bowel habit symptom with celiac disease, sometimes constipation may occur instead. Some people with celiac disease also experience headaches.


Constipation and headaches may occur as a side effect of several drugs. It is widely seen with opioid painkillers. These drugs affect bowel habit and often lead to constipation. Headaches may arise as these drugs wear off and is common in people who use these drugs to treat headaches or those who have become addicted to it. Constipation with headaches may also occur with certain statins which are used for lowering blood cholesterol levels.

Alcohol and Other Substances

Alcohol can also cause both constipation and headaches. This is more pronounced as part of a hangover. One of the main reasons for both these symptoms is dehydration. Alcohol is a diurectic that causes the loss of fluid and electrolytes. It can be severe dehydration when consumed in large quantities.

Many illicit substances can contribute to symptoms like headaches and constipation for several reasons. These substances affect nerve activity and can impede bowel motility which may contribute to constipation. Headaches may occur as a withdrawal symptom following intoxication.

Mental Health

Anxiety, depression and other mood disorders are some of the conditions where headaches are common symptoms. In many instances, constipation is also present although it is not always conclusively linked to the underlying mental health condition in every case. Even psychological stress can contribute to both headaches and constipation. Many people with these conditions may find constipation and headaches ease with anti-anxiety drugs, antidpressants and other anti-psychotic medication.

Other Possible Causes

  • Chronic fatigue syndrome
  • Systemic infections
  • Surgery, postoperative
  • Major trauma
  • Carcinoid tumors

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