Quick answer: Yes, constipation can cause nausea, especially when it's severe or has lasted several days. In studies, worse constipation tracks with worse upper-gut symptoms like nausea and fullness. Mild queasiness that eases after a bowel movement is common. Nausea with vomiting, belly swelling and being unable to pass gas is different. That can signal a bowel blockage, which needs emergency care.
Feeling sick to your stomach when you're backed up is a common complaint, and an unsettling one. Most of the time the explanation is ordinary: a full colon, pressure and bloating that dull your appetite. Occasionally nausea is the first sign that something more serious is going on.
This guide covers why constipation can make you nauseous, how to tell routine from urgent, and what to do about the headaches and dizziness people often mention too.
Key takeaways
- Constipation and nausea often travel together. In one study, upper-gut symptoms, including nausea and vomiting, worsened as constipation got more severe [2].
- Treating the constipation usually helps more than treating the nausea on its own.
- Vomiting + belly pain + being unable to pass gas = emergency. Those are classic signs of a bowel obstruction [3][4].
- The link with headaches is weaker. Studies show an association, but they don't show that constipation causes headaches [6].
- If nausea and constipation started together after a new medicine, such as a GLP-1 drug or a pain medicine, tell your prescriber [1][7].
Can constipation cause nausea?
Yes. It's not the most common constipation symptom, but it's a real one, and it's more likely the more backed up you are.
The clearest data comes from patients with upper-gut symptoms. In a study of 338 people with gastroparesis-type symptoms, those symptoms got worse as constipation got worse. That included the nausea and vomiting score [2]. Interestingly, worse constipation wasn't explained by slower stomach emptying. It went along with slower movement through the colon [2]. The researchers suggested part of the link may be sensory: a full, stretched gut can make the whole digestive tract more sensitive [2]. They concluded constipation is worth treating in its own right in people with nausea-type symptoms [2].
In everyday terms, constipation-related nausea usually looks like this:
- Queasiness and low appetite after a few days without a good bowel movement
- Fullness or bloating that makes food unappealing
- Relief after a bowel movement. This is one of the best clues that the two are linked.
If nausea doesn't ease when your bowels get moving, or it comes with other symptoms, look for another cause.
When is nausea with constipation an emergency?
When vomiting, belly pain, belly swelling and an inability to pass gas show up together. That combination can mean a bowel obstruction, a blockage that stops stool and gas from moving.
Cleveland Clinic lists obstruction symptoms (constipation, nausea and vomiting, belly pain and inability to pass gas) as reasons to seek emergency care [3]. Mayo Clinic adds crampy pain that comes and goes, loss of appetite and a swollen belly. It notes that, untreated, the blocked part of the intestine can be seriously damaged [4]. NIDDK also says to see a doctor right away if constipation comes with vomiting, inability to pass gas, constant belly pain, fever, blood in the stool or unintended weight loss [1].
Another warning sign is fecal impaction: a mass of hard stool stuck in the bowel. It can cause nausea, and some people leak watery stool around the blockage ("overflow"). That can look like diarrhea even though the real problem is constipation [5].
Nausea + constipation: what to do
| What you have | Likely meaning | What to do |
|---|---|---|
| Mild queasiness, passing gas, eases after a BM | Common with constipation | Self-care; track it |
| Nausea lasting several days, poor appetite, still passing gas | Constipation not resolving | Call your doctor; consider treatment options [8][9] |
| Watery leakage after days of no proper BM, with pressure or nausea | Possible fecal impaction [5] | See a doctor promptly |
| Vomiting, swollen belly, crampy pain, no gas | Possible bowel obstruction [3][4] | Emergency care now |
| Nausea + fever, blood in stool, or constant pain | Needs urgent assessment [1] | See a doctor right away |
For how long is "too long" without a bowel movement, see haven't pooped in days.
Can constipation cause headaches or dizziness?
Possibly linked, but not proven to be caused by it.
Some studies find that people with headaches report constipation more often. For example, a Brazilian study found constipation was associated with tension-type headache in women [6]. Association studies can't show which causes which, though. Shared factors like poor sleep, stress, dehydration, low food intake or medicines could drive both.
Dizziness is similar. If you're nauseated, eating and drinking less, and straining on the toilet, light-headedness isn't surprising. Dizziness that's new, severe or comes with fainting, chest pain or blood in your stool needs prompt medical attention. Don't put it down to constipation.
What causes nausea and constipation at the same time?
Often constipation itself. But it's worth checking for a common cause behind both:
- Medicines. NIDDK lists narcotic pain medicines, iron supplements, some antidepressants and antacids containing aluminum or calcium among drugs that cause constipation [1]. GLP-1 medicines are a growing example. In pooled trials of semaglutide 2.4 mg for weight management, nausea affected 43.9% of participants and constipation 24.2% (vs. 16.1% and 11.1% on placebo). Most of these effects were mild-to-moderate and happened around dose increases [7]. If you're on one, see our guide to tracking GI side effects on GLP-1s.
- Routine changes. Travel, changes in what you eat and ignoring the urge to go are listed causes of constipation [1].
- Other conditions. NIDDK lists diabetes, hypothyroidism and intestinal blockages among health problems that can cause constipation [1]. A doctor can sort these out.
Don't stop or change a prescribed medicine without talking to your prescriber [8].
What helps nausea from constipation?
Treat the constipation and the nausea usually follows. General first steps from NIDDK:
- Add fiber gradually and drink plenty of fluids, especially with fiber [8]
- Try for a bowel movement at the same time each day, 15–45 minutes after breakfast. Go when you feel the urge [8].
- Stay physically active if you can [8]
If you need more, the 2023 AGA–ACG guideline strongly recommends polyethylene glycol (PEG) for chronic idiopathic constipation. It recommends stimulant laxatives such as bisacodyl for short-term or rescue use [9]. Ask a pharmacist or doctor which fits you, especially if you're vomiting, pregnant, have kidney disease or take other medicines.
If you can't keep fluids down, or you're vomiting with no gas, don't try to treat it at home. Seek care [3][4].
How to track nausea and bowel movements
The question you want to answer is: does nausea rise when your bowels slow, and ease after you go? You can only see that with both in one log. Record:
- Each bowel movement: time and Bristol type
- No-go days, clearly marked
- Nausea: time and severity (0–3), plus whether it eased after a bowel movement
- Gas: yes/no. It matters for safety.
- New medicines or dose changes
Illustrative example: nausea tracking over five days
This is an illustrative example, not real user data.
| Day | Bowel movement | Bristol type | Nausea (0–3) | Passing gas? | Note |
|---|---|---|---|---|---|
| 1 | Yes, 8 am | 2 | 0 | Yes | — |
| 2 | No | — | 1 | Yes | Low appetite at lunch |
| 3 | No | — | 2 | Yes | Bloated |
| 4 | Yes, 9 am | 1, then 3 | 2 → 0 after BM | Yes | Nausea eased within an hour |
| 5 | Yes, 8 am | 4 | 0 | Yes | — |
Reading it: nausea built over two no-go days and eased after the day 4 bowel movement. That's a typical constipation-linked pattern. If day 4 had brought vomiting and no gas instead, that's the emergency row in the table above.
Our constipation diary guide has a printable layout with these columns.
For ongoing records, explore the Get Regular poop tracker. Compare the current logging workflow and access with the details you want to keep. An app record does not identify the cause of a bowel change.
When to see a doctor
Get emergency care for vomiting with a swollen belly, crampy pain and no gas or bowel movement [3][4].
See a doctor promptly if you have:
- Blood in or on your stool, or black, tarry stool
- Unintended weight loss
- Fever with constipation and nausea [1]
- New constipation that persists, especially if you're over 50
- Constipation alternating with thin stools
- Nausea that persists after your bowels move, or that keeps you from eating or drinking
- A family history of colon or rectal cancer [1]
Full checklist: when to see a doctor about bowel changes. If back pain is part of the picture, see can constipation cause back pain.
FAQ
Can constipation make you throw up?
Ordinary constipation usually causes queasiness rather than vomiting. Vomiting with constipation, especially with belly swelling or no gas, can signal a blockage and needs urgent care [3][4].
Why do I feel sick but can't poop?
A backed-up colon can cause fullness, bloating and nausea. Studies link more severe constipation with more upper-gut symptoms [2]. If you can still pass gas and the nausea is mild, it's usually constipation. If you can't pass gas or you're vomiting, seek care.
Can constipation cause loss of appetite?
Yes. Loss of appetite is common when you're backed up, and it's also listed among obstruction symptoms [4]. If appetite loss lasts, or comes with weight loss, see a doctor.
Will a laxative help with constipation nausea?
If the nausea comes from constipation, relieving the constipation usually helps. Guideline-backed options include PEG, and stimulant laxatives for short-term use [9]. Don't take a laxative if you're vomiting, can't pass gas or have severe belly pain. Get checked first.
Can constipation cause dizziness?
Not directly in most cases. Eating and drinking less, straining and nausea can make you light-headed. New or severe dizziness, fainting or chest symptoms need medical attention.
Sources
- NIDDK. Symptoms & Causes of Constipation. https://www.niddk.nih.gov/health-information/digestive-diseases/constipation/symptoms-causes
- Parkman HP, et al. Constipation in Patients With Symptoms of Gastroparesis: Analysis of Symptoms and Gastrointestinal Transit. Clin Gastroenterol Hepatol. https://www.cghjournal.org/article/S1542-3565(20)31503-2/fulltext
- Cleveland Clinic. Changes in Bowel Habits. https://my.clevelandclinic.org/health/symptoms/changes-in-bowel-habits
- Mayo Clinic. Intestinal obstruction — Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/intestinal-obstruction/symptoms-causes/syc-20351460
- Cancer Research UK. Chronic constipation and faecal impaction. https://www.cancerresearchuk.org/about-cancer/coping/physically/bowel-problems/types/chronic-constipation
- Constipation is associated with tension-type headache in women. Arq Neuropsiquiatr. https://www.scielo.br/j/anp/a/Gt4B7NrQyMGmrVhp9g7bwKK/?lang=en&format=pdf
- Pooled analysis of STEP 1–3 trials: gastrointestinal adverse events with once-weekly semaglutide 2.4 mg. https://pmc.ncbi.nlm.nih.gov/articles/PMC9293236/
- NIDDK. Treatment for Constipation. https://www.niddk.nih.gov/health-information/digestive-diseases/constipation/treatment
- Chang L, Chey WD, Imdad A, et al. AGA–ACG Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation. Gastroenterology. 2023;164(7):1086–1106. https://gastro.org/clinical-guidance/pharmacological-management-of-chronic-idiopathic-constipation-cic/
This article is for general education and isn't medical advice. Get Regular is a tracking app — it doesn't diagnose or treat any condition. If you have red-flag symptoms or ongoing changes in your digestion, talk to a doctor.