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Nitrofurantoin 100mg MR capsules are one of the two first-choice antibiotics for cystitis and other uncomplicated UTIs in UK guidance. For women aged 18 to 64, prescribed after an online consultation with a GPhC-registered pharmacist independent prescriber.
This service is for women aged 18 to 64 with symptoms of cystitis. It isn’t suitable if you’re pregnant or breastfeeding, have kidney disease, or have back pain, a high temperature or shivering, which can be signs of a kidney infection. Please see your GP or call NHS 111 instead.
Order before 3pm — same-day dispatch (MON - FRI)
~5 min consultation
Secure & confidential · Reviewed by a UK prescriber
Suitable age
18 to 64 years
Max per order
1 pack
Consultation
✓ Yes — online consultation
Nitrofurantoin is an antibiotic used to treat cystitis, the most common type of urinary tract infection (UTI) in women. It’s concentrated in the urine, where it damages the bacteria that cause most bladder infections, such as E. coli, while reaching only low levels in the rest of the body. NICE recommends it, alongside trimethoprim, as a first choice for women with cystitis, provided the kidneys work normally. Resistance to it is uncommon.
The MR (modified-release) capsule releases the medicine slowly, so you only need to take it twice a day. The usual course is one capsule twice a day with food for 3 days. Our nitrofurantoin guide covers how to take it and what to expect, and UTI antibiotics in the UK compares it with trimethoprim. You can see all the options on our cystitis treatment online page.
| Medicine type | Antibiotic |
| Active ingredient | Nitrofurantoin 100mg (modified release) |
| Used for | Cystitis (uncomplicated lower urinary tract infection) in women |
| Dose | One capsule twice a day, with food or milk |
| Course | Usually 3 days (6 capsules); 7 days (14 capsules) only if your prescriber decides it’s needed |
| Prescription status | Prescription-only medicine (POM) |
| Suitable for | Women aged 18 to 64 with normal kidney function, not pregnant or breastfeeding |
| UK guidance | NICE NG109 |
Nitrofurantoin may be suitable if you: - are a woman aged 18 to 64; - have typical cystitis symptoms: burning when you pee, needing to pee often or urgently, or pain low in your tummy; - have normal kidney function; - aren’t pregnant or breastfeeding.
This service isn’t suitable if you: - are a man, under 18 or aged 65 or over; - are pregnant, might be pregnant, or are breastfeeding; - have back or side pain, a high temperature, shivering or vomiting (signs of a kidney infection); - can see blood in your urine; - have had 2 urine infections in the last 6 months, or 3 in the last year. Your GP can arrange a urine culture; - have kidney disease, a catheter or a weakened immune system; - have unusual vaginal discharge or itching, which may be thrush or an STI.
You can’t take nitrofurantoin if you have: - reduced kidney function (eGFR below 45); - G6PD deficiency; - acute porphyria; - ever had a reaction to nitrofurantoin, including lung or liver problems.
Tell the prescriber if you: - have lung disease, liver disease, nerve problems (such as numbness in the hands or feet), anaemia, diabetes, or low vitamin B or folate; - take indigestion remedies containing magnesium trisilicate, probenecid, sulfinpyrazone, quinolone antibiotics (such as ciprofloxacin) or acetazolamide; - use cystitis relief sachets such as CanesOasis. They make urine less acidic, which stops nitrofurantoin working as well, so don’t use them together.
If nitrofurantoin isn’t right for you, trimethoprim is the other first-choice antibiotic. See our trimethoprim guide.
Nitrofurantoin is a prescription antibiotic for cystitis and other uncomplicated urinary tract infections in women. It’s concentrated in the urine, where it damages several parts of the bacteria that cause bladder infections, so they can’t survive. Because it reaches only low levels elsewhere in the body, it’s used for bladder infections, not kidney infections. Our nitrofurantoin guide explains more.
Many women start to feel better within a day or two. Keep taking it for the full course, even if you feel better sooner. If your symptoms haven’t started to improve within 48 hours, or they get worse, contact your GP or NHS 111, as you may need a urine test and a different antibiotic.
Take one 100mg MR capsule twice a day, about 12 hours apart, with food or a glass of milk. The usual course for cystitis in women is 3 days, as NICE recommends. Your prescriber may give a 7-day course if it’s needed. Swallow the capsules whole, and finish whichever course you’re given.
Yes, it often turns urine dark yellow or brown. This is harmless and goes back to normal after you finish the course. If your urine looks red, or you see blood, contact your GP, as this isn’t caused by the medicine.
The ones reported most often are feeling sick, loss of appetite, tummy pain, diarrhoea, headache and dizziness; taking it with food helps. Rarely, it can affect the lungs, liver or nerves. Stop taking it and get help if you develop breathlessness or a cough, yellow skin or eyes, or numbness or tingling. See our nitrofurantoin guide for more.
It isn’t suitable if your kidneys don’t work well (eGFR below 45), because it won’t reach high enough levels in the urine to work and may build up. It also isn’t suitable if you have G6PD deficiency or acute porphyria, or have had a reaction to it before. Tell the prescriber about lung, liver or nerve problems, and any medicines you take.
There’s no direct interaction, but alcohol can make sickness and dizziness worse and irritate your bladder, which can make cystitis feel worse. It’s best to avoid it, or keep it to a minimum, until you’ve finished the course and feel better.
Not through our online service. Urine infections in pregnancy need a urine test and a treatment plan from your GP or midwife. Nitrofurantoin must not be taken near the end of pregnancy, as it can affect the baby’s blood. Please contact your GP or midwife the same day. If you’re breastfeeding, see your GP or a pharmacist.
No. Cystitis relief sachets such as CanesOasis contain sodium citrate, which makes urine less acidic. That reduces how well nitrofurantoin works. If you’re taking nitrofurantoin, use paracetamol or ibuprofen for pain instead, if they’re suitable for you.
Both are first-choice antibiotics in UK guidance. Nitrofurantoin is often preferred because resistance to it is less common, but it isn’t suitable if your kidneys don’t work well. Trimethoprim is a good alternative if you haven’t taken it in the last 3 months. Our UTI antibiotics guide compares them.
Nitrofurantoin 100mg MR comes in two packs: 6 capsules (a 3-day course, £12.99) and 14 capsules (a 7-day course, £16.99). The 3-day course is the usual treatment for cystitis in women, as UK guidance recommends. The prescriber supplies the 14-capsule pack if they decide a longer course is needed, so you don’t need to choose: just complete the consultation and they’ll pick the right course.
Helpful articles and clinical guides related to this treatment category.
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