Wegovy constipation: causes, relief and the warning signs of a blocked bowel

Constipation is one of the seven very common Wegovy side effects and the one people tend to put up with longest before asking for help. It is usually straightforward to manage once you understand that the medicine is slowing your gut and quietly cutting your fluid intake at the same time. This guide covers the mechanism, a step-by-step relief plan, what to ask a pharmacist for, and the specific combination of symptoms the leaflet lists for bowel obstruction.

Constipation: very commonBowel obstruction: frequency not knownChecked 20 October 2026Author: Nick Johnson

Key facts

Constipation is very common on Wegovy: more than 1 in 10 people. In STEP 1 it was reported by roughly a quarter of people on 2.4 mg, against under a tenth on placebo.
It is driven by slower gut movement, smaller food volume, less fibre and, above all, less fluid.
Fluids and gradual fibre fix most cases; a pharmacist can suggest a suitable laxative when they do not.
Swinging between constipation and diarrhoea in the first weeks is normal.
Bowel obstruction is listed in the leaflet with a frequency that cannot be estimated: severe constipation together with stomach ache, bloating and vomiting. That combination needs prompt medical assessment, not more laxatives.

Why Wegovy causes constipation

Semaglutide slows the movement of food through the whole digestive tract, not just the stomach. Slower transit means more water is absorbed from the stool in the large bowel, leaving it harder and drier. Three habits that come with the medicine make it worse. You eat less, so there is less bulk to push through. You often eat less fibre, because the foods that feel easiest on a queasy stomach (toast, rice, plain chicken) are low in it. And you drink less, because the appetite suppression that makes the medicine work also dampens thirst.

The pattern is usually worst in the first weeks and after each dose increase, and settles as the gut adjusts. It is not a sign of anything going wrong, but it should not be ignored either, because the leaflet's most serious bowel entry is a severe form of constipation.

How common it is

STEP 1 (68 weeks)	Wegovy 2.4 mg	Placebo
Constipation	about 23%	about 10%
Diarrhoea	about 32%	about 16%

The two overlap: many people alternate between them in the escalation phase. Diarrhoea is covered on the dehydration guide because fluid loss is the thing that matters with it.

A step-by-step relief plan

1. Fluids first

Aim for regular drinks through the day whether or not you feel thirsty. Pale yellow urine is the simple check. Warm drinks in the morning help many people get going.

2. Add fibre gradually

Oats, fruit with the skin on, vegetables, beans, lentils and wholegrains. Increase over a week or two rather than all at once, because a sudden jump in fibre on a slow gut causes bloating and wind. Fibre only works with enough fluid. Without it, it makes things worse.

3. Move

A daily walk, even a short one, stimulates the bowel. It also helps with the tiredness that often comes with the first months.

4. Do not hold on

Go when you feel the urge. A footstool that raises your knees above your hips makes it easier to pass a stool.

5. Ask a pharmacist about a laxative

If a week of the above has not worked, a pharmacist can suggest a suitable product. Osmotic laxatives (which draw water into the stool) and bulk formers are usually first choices; stimulant laxatives are for short-term use. Tell the pharmacist you are on Wegovy and what else you take. Do not combine several laxatives on your own initiative.

6. Tell your prescriber before the next step up

If constipation has not settled at the end of a four week step, say so before the dose goes up. Staying an extra four weeks is a licensed, normal option.

When constipation needs assessment

Possible bowel obstruction. The leaflet describes a severe form of constipation with additional symptoms such as stomach ache, bloating and vomiting. If you have not opened your bowels for several days and now have stomach pain, a swollen abdomen and vomiting, or cannot pass wind, contact NHS 111 or go to A&E. Do not take more laxatives while waiting.

See a GP or use NHS 111 for blood in the stool, black tarry stools, unexplained weight loss beyond what you expect from treatment, constipation alternating with diarrhoea that does not settle after the escalation phase, or constipation lasting more than three weeks despite the steps above.

Severe, persistent stomach pain on its own, with or without nausea, is the pancreatitis warning sign: stop Wegovy and get urgent help. See the pancreatitis guide.

Frequently asked questions

How long does Wegovy constipation last?

It usually eases within a few weeks of each dose step as the gut adapts, and settles further at maintenance. Constipation that persists for more than three weeks despite fluids, fibre and a pharmacist-recommended laxative should be reviewed.

Which laxative is best on Wegovy?

There is no single best. Osmotic and bulk-forming laxatives are the usual first choices; stimulants are for short bursts. A pharmacist will choose based on your other medicines, so ask rather than self-select, and never stack several types.

Can Wegovy cause a blocked bowel?

Bowel obstruction is listed in the leaflet with a frequency that cannot be estimated from available data, meaning it has been reported but is not common. The signs are severe constipation together with stomach ache, bloating and vomiting. That combination needs prompt assessment.

Why do I swing between constipation and diarrhoea?

Both are very common in the escalation phase because the gut is adjusting to slower transit and changed eating. It typically settles at maintenance. If it does not, mention it to your prescriber.

Does eating more fibre make Wegovy nausea worse?

A sudden large increase can, because it adds bulk and gas to a slow stomach. Add fibre gradually with plenty of fluid and it is usually fine.

Sources and about this guide

Wegovy FlexTouch patient information leaflet, revised June 2026 (eMC)
Wegovy Summary of Product Characteristics (eMC)
Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine 2021; 384: 989-1002.
NHS: constipation
NHS: bowel obstruction

Written by Nick Johnson, founder of Medstack Ltd and Independent Prescription Pricing Analyst. Checked 20 October 2026 against the June 2026 leaflet. Next review 5 December 2026. iGovy is an independent price comparison site. It does not sell, prescribe or dispense medicines, and this page is general information, not medical advice. No clinician has reviewed it yet. A named reviewer will be added when appointed.

How this guide was checked: every frequency statement was compared line by line with section 4 of the Wegovy FlexTouch patient leaflet revised June 2026 and section 4.8 of the Summary of Product Characteristics on the eMC. Trial figures are quoted from the published STEP papers or the SmPC, never from pharmacy marketing, and NHS pages are used for symptom guidance. The page is re-checked whenever the eMC record changes or the MHRA issues a Drug Safety Update, and at least every three months.

Funding and independence: iGovy earns referral commission when readers use pharmacy discount codes on its price pages. No pharmacy or manufacturer paid for, saw or influenced this guide, and health content is not affected by commercial arrangements. Full policy on the editorial policy page. Corrections via the contact page.