I'm on Hydrea 5500mg/week for ET, which has been the dose for a few months now. Platelets are now normal (low 300's), but I believe that I will be on a maintenance dose when I next see my haematologist at the end of May. I have suffered with constipation since day 1. Recently my GP prescribed a safer treatment - Osmolax (macrogol) when I mentioned my problem.
My question is whether my constipation will be a lifelong condition or will a lower/maintenance dose return my regularity?
222Bobby, there is a chance the lower level will bring you back to normal. Hydrea causes loss of magnesium needed to convert vitamin B1 (thiamine) into the bioactive form. These links explaining thiamine and the vagus nerve offer one possibility for relief you can discuss with your doctor.
I use psyllium husks on orange juice with breakfast and they work like a charm. Stay hydrated though or they turn to a “brick” inside😊
You're spot on - I found they were the most helpful way to ease this difficult side effect, but in the 90s my brother, a district nurse, saw me mixing up one dose and said I must drink an extra glass of water afterwards and keep hydrated all day
This was when my haematologist and GP denied HU was causing it nor mentioned that we should keep hydrated anyway and just muttered about diet and exercise. I never want to see bran flakes again! I was seen as as somewhat eccentric at keeping a large glass of water at my desk all day - wouldn't nowadays. I'm afraid the problem continued, but under control as long as I swallowed ' the mixture', until I was shifted to Anagrelide.
Carrots - every day - wash well but don't peel, just top and tail. Eat as a 'side' with your main meal or grated raw (nice snack, takes a while to eat) with walnuts, sultanas, and a little oil such as walnut or garlic. Beetroot too - 'sweet pickled' as it is or added (chopped) to the carrot. Takes time to prepare - which is nice too. And I have a recipe for Chocolate and Treacle cup cakes if you like......
try red wine , I have no problems.
HU caused the same problem for me. Lower doses did not resolve the problem for me. It took several months after I discontinued HU to get back to normal.
HU has a number of adverse effects on GI function. It can compromise the intestinal endothelium, It is also an anti-bacterial and can disrupt the gut microbiome. As Pte82 points out it can also impact how you metabolize nutrients.
There are things you can try to manage the problem. Miralax (an osmotic agent) is one option. Also very important to keep up your fluid intake. Increasing fiber content in your diet, fruits that have higher levels of sorbitol, and probiotics can all help as well.
Hope you get the issue resolved soon as it is quite bothersome.
Hydrea did cause constipation for me too. I found that I could keep things "working" fairly well by having home made muesli every day that consisted mostly of oats (with sunflower seeds, a few nuts and so on) adorned with dried figs, prunes, and raisins. Also having some onion in my main meal of the day was helpful if things were difficult. I am no longer on Hydrea (I'm now on Anagrelide), and am happy to report that the constipating effects of the Hydrea gradually wore off 2 - 3 weeks after stopping it.
No problems for me as long as I have a sensible diet.
Just as before - timings not as regular as before I retired - but that is lack of routine!
Hydroxycarbamide really upset my gut with diarrhoea and constipation, and wind. Stress at work, irregular meals and not enough fluid all made things worse. Retirement was a blessing.
I found the book Gut by Giulia Enders very helpful.
We have plenty of vegetables in soup or salad for lunch and steamed with dinner. We have half a banana each and some blueberries in porridge, and half an orange at breakfast and a glass of home made kefir.
We have fruit for snacks and one homemade fruit loaf a week.
We have one Asda seeded wholemeal loaf a week. I have cut down on pasta, potatoes and rice and sugar.
We have had a healthy diet for two for £30 a week ‘click and collect’ from Asda for over a year now.
Plenty of fluids, not enough exercise, but no constipation.
Hydrea 
To take Hydrea or not
Chronic Belly Bloating on Hydrea
First time taking hydrea
