If you’ve been prescribed Xylox tablets, they contain the drug letrozole, an Indian brand not licensed in the UK. Here, letrozole is sold as Femara or, more commonly, as a generic. It’s used mainly for hormone receptor-positive breast cancer in postmenopausal women and, off-label, for fertility. Common side effects include hot flushes and joint pain, with bone thinning being a key long-term concern. To continue treatment in the UK, speak to your GP or oncology team to switch to an NHS-prescribed version.
If you’ve been handed a box of Xylox tablets abroad or seen the name mentioned online, you’re likely looking for clarity. The important thing to know is that Xylox is a brand name for a specific medication, and understanding its UK equivalent is essential for safe and effective continuing care. This piece explains exactly what Xylox is, how it maps to medicines in the UK, what letrozole is used for, its side effects, and how NHS prescribing works — so you can have an informed conversation with your GP or oncology team.
What Xylox actually is — a brand-name clarification
The tablet branded ‘Xylox 2.5mg’ is a formulation of the drug letrozole, manufactured by Bafna Pharmaceuticals in India. It is not a brand that is licensed or marketed in the United Kingdom. In the UK, the same active ingredient, letrozole, is available in two primary forms: as the original brand ‘Femara’, historically made by Novartis, and more widely as a generic medicine simply called ‘letrozole’. The NHS predominantly prescribes generic letrozole. All three — Xylox, Femara, and generic letrozole — contain exactly the same active drug at the same 2.5mg dose.
Worth knowing: other products share the Xylox name but are completely different medicines. Themis Medicare Ltd, for example, markets a lidocaine gel and injection under the Xylox brand, used as a local anaesthetic. There are also nasal sprays containing xylometazoline that can have similar names. When people in the UK search for ‘Xylox tablet’, they are almost certainly referring to the letrozole tablet for breast cancer or fertility treatment. This article focuses solely on that context. Always check the active ingredient and consult a healthcare professional if you are unsure.
How letrozole works — the aromatase inhibitor mechanism in plain English
Letrozole belongs to a class of drugs called aromatase inhibitors. To understand its role, you need a bit of biology. In postmenopausal women, the primary source of the hormone oestrogen isn’t the ovaries (which have stopped producing it), but a process where an enzyme called aromatase converts other hormones (androgens) into oestrogen in body tissues like fat.
Some breast cancers are stimulated to grow by oestrogen; these are known as hormone receptor-positive (HR+) or oestrogen receptor-positive (ER+) cancers. Letrozole works by blocking the aromatase enzyme. With this enzyme inhibited, the body’s ability to produce oestrogen is dramatically reduced. This ‘starves’ the ER+ cancer cells of the hormone they need to multiply, helping to slow or stop the cancer’s growth.
This mechanism is why letrozole is primarily used in postmenopausal women. In premenopausal women, the ovaries produce large amounts of oestrogen that overwhelm the effect of an aromatase inhibitor. For them, other drugs that block oestrogen receptors, like tamoxifen, are typically used first. The exception is in certain fertility treatments, where a short course of letrozole’s oestrogen-lowering effect can be used to stimulate ovulation.
The licensed UK uses — what letrozole is prescribed for
In the UK, letrozole has several licensed uses approved by the MHRA (Medicines and Healthcare products Regulatory Agency) and is recommended by NICE (National Institute for Health and Care Excellence). Its primary role is in treating postmenopausal women with hormone receptor-positive breast cancer. This includes as an ‘adjuvant’ therapy after initial treatment (like surgery) to reduce the risk of the cancer returning, typically for five to ten years. It’s also used as ‘neo-adjuvant’ treatment before surgery to shrink a tumour.
For women who are not candidates for surgery, letrozole can be a first-line treatment. It is also used to treat advanced or metastatic breast cancer that has spread to other parts of the body. Furthermore, it’s prescribed as ‘extended adjuvant’ therapy after a patient has completed a course of another hormone therapy, tamoxifen. The standard dose across these uses is 2.5mg taken orally once a day, with or without food. As noted by Cancer Research UK, taking it at the same time each day can help you remember, but the exact timing isn’t strictly critical.
The off-label UK use — letrozole for fertility
First-line ovulation induction in PCOS since 2013
While its main licence is for cancer, letrozole is widely used ‘off-label’ in the UK for ovulation induction in women with polycystic ovary syndrome (PCOS). NICE has recommended it as a first-line treatment for this purpose since 2013, often preferring it over the older drug clomifene due to better efficacy and lower multiple pregnancy rates in this group.
In this context, it’s usually prescribed by a fertility clinic or an endocrinologist, not a GP. The treatment involves taking a short course of letrozole for a few days at the start of the menstrual cycle to encourage the release of an egg. The dosage and monitoring (including ultrasound scans) are different from the continuous daily dose used in cancer care. If you’re using letrozole for fertility, you should be under the care of a specialist who can tailor the treatment to your specific needs.
Side effects — what UK patients actually report
Like all medicines, letrozole can cause side effects, though not everyone gets them. According to NHS and Macmillan Cancer Support patient information, the most commonly reported ones are hot flushes and night sweats, which can be very frequent and bothersome. Joint pain and stiffness (arthralgia), particularly in the hands, knees, and hips, are also very common and can impact daily life.
Many patients report fatigue, headaches, and trouble sleeping. Some experience low mood or feelings of anxiety. Hair thinning is a recognised, though often distressing, side effect. Mild nausea and indigestion can occur, usually improving after the first few weeks of treatment. It’s important to be aware that side effects like these can affect your quality of life over what is often a long treatment period. Breast Cancer Now emphasises that you should not simply ‘put up with’ them; discuss any troublesome side effects with your oncology team or GP, as there may be ways to manage them or alternative treatments to consider.
The bone-loss issue — the long-term side effect that matters most
⚠️ The one to actively monitor
One of the most significant long-term concerns with letrozole is its effect on bone density. Oestrogen, even at the lower levels after menopause, helps protect bones. By further reducing oestrogen, letrozole can accelerate bone thinning, increasing the risk of osteoporosis and fractures over time.
Because of this, UK clinical practice is proactive. As recommended by organisations like The Royal Marsden NHS Foundation Trust, you should have a baseline DEXA bone density scan before or soon after starting treatment. This scan is typically repeated every two years to monitor your bone health. If bone loss is detected, your doctor may prescribe bisphosphonates (like alendronic acid) or denosumab to strengthen bones. You’ll also be advised to take calcium and vitamin D supplements. Incorporating weight-bearing and strength-training exercise is another important, non-drug strategy to help mitigate this risk. This side effect is manageable, but only if it’s actively monitored.
Who shouldn’t take letrozole
Letrozole is not suitable for everyone. It should not be used by premenopausal women, as their ovaries produce high levels of oestrogen that the drug cannot adequately suppress — unless it is being specifically prescribed off-label for fertility induction under specialist care. It is absolutely contraindicated in pregnancy, as it can cause harm to a developing baby. Women who could become pregnant must use effective non-hormonal contraception during treatment and for a short period after stopping.
People with severe liver impairment should generally not take letrozole. You must not take it if you have a known hypersensitivity (allergy) to letrozole or any of the tablet’s inactive ingredients. If you suspect you have become pregnant while on letrozole for cancer treatment, stop taking the tablets immediately and contact your oncology team or GP for urgent advice.
If you’ve been prescribed Xylox abroad — what to do in the UK
If you were prescribed Xylox in another country and have returned to the UK, or if you are considering purchasing it online, the safest and most effective course of action is to integrate into the UK healthcare system. Letrozole is readily available on the NHS.
Book an appointment with your GP. If you’re taking it for cancer, it’s best to ask for an urgent referral to a local oncology team, or contact your previous team for a handover. Bring the original packaging with you so the UK prescriber can see the exact brand, dose, and prescribed duration. They will almost certainly switch you to UK-licensed generic letrozole or Femara, which is the same medication. As the MHRA does not regulate medicines sold from overseas pharmacies, the quality and authenticity of imported drugs like Xylox cannot be guaranteed. For cancer patients, remember that you are exempt from NHS prescription charges (currently £9.90 per item in England) and can apply for a Medical Exemption Certificate (FP92A) via your GP or oncology department.
Frequently Asked Questions
Xylox tablets are letrozole. UK = Femara or generic.
Medication names from abroad can be confusing to decode, but the core of this one is simple: Xylox tablets are letrozole. In the UK, you’ll receive this drug under its proper name, through the NHS pathway, ensuring quality and proper monitoring. Whether you’re continuing treatment or starting it anew, your GP and specialist team are your best resource.
Related reading: NHS: Letrozole · Cancer Research UK: Letrozole (Femara) · Breast Cancer Now: Letrozole
