Psyllium Husk: Benefits, How Much to Take, Side Effects and Fybogel (UK)

What is psyllium husk?

Psyllium husk is the outer coating of the seeds of Plantago ovata, a plant grown mainly in India. It is mostly soluble, gel-forming fibre, so it holds water in the gut. You can buy it as whole husk, finer husk powder or capsules, and as ispaghula husk, the licensed bulk-forming laxative in Fybogel.

If you want to raise your fibre from food first, see our high fibre foods list, which shows grams per portion for everyday foods.

Psyllium husk benefits: what the evidence shows

Psyllium has the strongest evidence of any fibre supplement for chronic constipation, with trials showing more frequent, softer stools at doses above 10g a day taken for at least 4 weeks. It also lowers LDL cholesterol slightly. Blood sugar effects are seen mainly in people whose blood sugar is already raised, and it doesn’t reliably help weight loss.

NICE’s IBS guideline says that if more fibre is advised, it should be soluble fibre such as ispaghula powder, or oats, rather than insoluble fibre such as bran. Our IBS guide covers the full NICE approach, and foods that help constipation compares psyllium with kiwi and prunes, which did as well in some trials.

Does psyllium have an authorised health claim?

No. There is no authorised health claim for psyllium in Great Britain, so products can’t legally say it lowers cholesterol or keeps you regular. Other fibres do have claims: oat and barley beta-glucans contribute to the maintenance of normal blood cholesterol levels, and wheat bran fibre contributes to an acceleration of intestinal transit. A psyllium product can still be labelled “high fibre”, which is a nutrition claim.

How much psyllium husk should you take a day?

Most adults start with about 3 to 5g of psyllium husk once a day in a full glass of water, then build up over 1 to 2 weeks. Trials for constipation and cholesterol mostly used about 10g a day, split into 2 or 3 doses. Fybogel’s adult dose is one 3.5g sachet twice a day, which is 7g.

Psyllium counts towards your 30g of fibre a day, so if you already eat plenty of beans, oats, fruit and vegetables you may need less. Spoon sizes vary a lot between husk and powder, so go by the grams on your pack rather than teaspoons.

How to take psyllium husk safely

Always mix psyllium husk into at least 150ml of water or another drink, stir and drink it straight away, then keep drinking fluids through the day. Never swallow the powder dry. Taken with too little water, psyllium can swell and block the throat, gullet or bowel.

• Water with every dose: at least 150ml, the NHS amount for Fybogel. Capsules need a full glass too.
• After a meal or snack: the NHS suggests taking Fybogel after food.
• Not just before bed: take the evening dose at least an hour before bed.
• Build up slowly: a sudden jump in fibre is the main cause of wind and bloating.
• Don’t breathe in the powder: inhaled psyllium dust can rarely cause an allergic reaction.

Choking and blockages are rare, but case reports describe the gullet blocking when psyllium was taken with too little water, especially in people who have trouble swallowing. If psyllium seems to stick in your throat, or you get chest pain or can’t swallow after taking it, get urgent medical help.

Psyllium husk and medicines

Psyllium can change how other medicines, vitamins and supplements are absorbed. The NHS advises taking any other medicine or supplement more than an hour before or after Fybogel. We suggest leaving 2 hours where you can, and asking a pharmacist about medicines where timing matters.

The NHS says to tell your pharmacist or doctor before starting if you take:

• lithium, for mood problems
• carbamazepine, for epilepsy and mood problems
• digoxin, a heart medicine
• insulin or any other diabetes medicine, as your dose may need adjusting
• mesalazine, for bowel disease
• pain medicines that cause constipation, such as codeine

iThis isn’t a full list. If you take thyroid tablets, the contraceptive pill or any medicine where steady levels matter, check the timing with your pharmacist. Only take two types of laxative together if a doctor or pharmacist recommends it.

Psyllium husk side effects and who should avoid it

The common side effects of psyllium husk are wind and bloating, which often ease within a few days as your gut adjusts. Rarely, psyllium causes an allergic reaction. Anyone with swallowing problems, signs of a bowel blockage or a weak bowel should check with a doctor before taking it.

iCheck with a doctor or pharmacist first if you have:

• difficulty swallowing or any throat problems
• tummy pain with feeling or being sick, which could be signs of a blockage
• muscle weakness of the bowel (colonic atony)
• phenylketonuria, as some flavoured sachets contain aspartame
• had an allergic reaction to psyllium or ispaghula before

The NHS says most adults can take Fybogel, including during pregnancy and breastfeeding, and children under 6 should only have it if a doctor prescribes it. Call 999 if your lips, mouth, throat or tongue swell, or your throat feels tight. See a GP if constipation hasn’t improved after 3 days of taking it, or if you notice blood in your poo or a change in your bowel habits. Our guide to signs of poor gut health explains which symptoms need checking.

Psyllium husk vs Fybogel: what’s the difference?

Psyllium husk and Fybogel contain the same fibre. Fybogel is ispaghula husk, another name for psyllium husk, sold as a licensed medicine for constipation in measured 3.5g sachets. Plain psyllium husk is sold as a food supplement, usually cheaper per gram, but it can’t make medicinal claims and its dose is up to you.

iIf you want a measured, licensed product for constipation, ask a pharmacist about ispaghula husk. Our supplements for digestion guide ranks psyllium against peppermint oil and probiotics.

Psyllium vs other fibre supplements

Psyllium forms a thicker gel than most fibres and holds on to water through the gut, which is why it softens hard stools. Inulin is fermented quickly by gut bacteria, so it tends to cause more wind. Chia and ground flaxseed add fibre as food. Magnesium citrate works differently, by drawing water into the bowel.

See chia seeds benefits, magnesium citrate and magnesium for constipation for more. For bloating rather than constipation, read magnesium for bloating and our gut health guide. If cholesterol is your focus, see does stress cause high cholesterol?