Prometrium (Progesterone) – Patient Information (UK)

Prometrium is a brand of micronised progesterone, a natural form of the hormone progesterone. It is used to support hormonal balance in specific conditions, most commonly related to the reproductive system and, in some cases, the management of symptoms caused by changes in hormone levels.

This page explains how Prometrium works, how it is typically used, what to expect, and important safety information. It is written for patients in the United Kingdom.

Quick Facts

• Medicine name: Prometrium (progesterone)
• Type: Hormone (progestogen) therapy
• Typical form: Oral soft capsules
• Who it may be for: People who need progesterone to protect the womb lining (endometrium) or to support certain reproductive treatments (as directed by a healthcare professional)
• Key points: Progesterone helps counter the effects of oestrogen on the uterus and supports normal menstrual and pregnancy-related hormone functions

Basic Product Information

Important: Prometrium should be used exactly as advised for your specific situation. Dosing differs depending on the reason for use, the treatment schedule, and your medical history.

How Prometrium Works (Mechanism of Action)

Progesterone is a hormone that prepares and stabilises the endometrium (the lining of the uterus). Its actions include:

• Endometrial protection: In people who have a uterus and are taking oestrogen, progesterone helps prevent excessive growth of the endometrium, which can increase the risk of abnormal changes.
• Secretory transformation: Progesterone turns the endometrium into a secretory state suitable for implantation and maintenance of early pregnancy.
• Hormonal regulation: Progesterone influences feedback loops involving the hypothalamus and pituitary, affecting ovulation and cycle patterns.
• Symptom support: By changing hormonal effects on reproductive tissues, progesterone can help with symptoms associated with hormonal imbalance (for example, in certain menopausal hormone therapy regimens when used alongside oestrogen).

Pharmacokinetics (How the Body Handles Prometrium)

Pharmacokinetics describes absorption, distribution, metabolism, and elimination.

Absorption

Prometrium is micronised progesterone, designed for good oral absorption. After taking the capsule, progesterone is absorbed through the digestive tract and begins to exert effects on target tissues.

Distribution

Progesterone circulates in the bloodstream and is distributed to hormone-responsive tissues, including the uterus and reproductive tissues.

Metabolism

Progesterone is primarily metabolised in the liver. Its breakdown products are then further processed and prepared for elimination.

Elimination

Metabolites are eliminated mainly via the kidneys (through urine) and to a smaller extent via other routes, depending on the specific metabolite profile.

Practical takeaway: Because progesterone is processed in the body (including the liver), other medicines and alcohol may affect tolerability or side effects in some people.

Typical Uses in the UK

Prometrium may be used for different clinical indications depending on your individual circumstances. Common reasons include:

• Endometrial protection in people who have a uterus and are taking oestrogen as part of menopausal hormone therapy (MHT).
• Hormone support in fertility treatment pathways, where progesterone is used to support the uterine lining and early pregnancy environment (the exact regimen varies by clinic plan).
• Other progesterone-responsive conditions as determined by a healthcare professional.

Note: The appropriate use and regimen depend strongly on your medical diagnosis and whether you still have your uterus.

Timing: When to Take Prometrium

Timing depends on the intended treatment schedule.

Common scheduling approaches

• Continuous daily dosing: Sometimes used as part of hormone support regimens.
• Cyclic (part of the month) dosing: Often used when progesterone is added for a defined period alongside oestrogen.
• Evening administration: Many people choose evening dosing because progesterone can cause drowsiness or a “sedating” feeling in some individuals.

How to stay consistent

• Try to take your capsule at about the same time each day.
• If you feel sleepy, consider taking it in the evening (unless your clinician has advised otherwise).
• If you miss a dose, follow the guidance provided with your product and your clinician’s instructions.

Food Interactions

Food may affect how quickly a medicine is absorbed, but micronised progesterone is generally taken by mouth without strict dietary restrictions.

Patient-friendly approach:

• You can usually take Prometrium with or without food, but if your stomach feels sensitive, taking it with a meal may reduce nausea or discomfort.
• If your regimen is tied to a specific fertility schedule, follow your clinic’s timing instructions closely.

If you develop persistent stomach upset (e.g., nausea, vomiting, diarrhoea), speak with a healthcare professional for advice.

Alcohol and Medicines Interactions

Alcohol

Alcohol can worsen side effects such as sleepiness, dizziness, and reduced alertness. In some people, it may also increase the likelihood of feeling unwell.

• Avoid heavy drinking while taking Prometrium.
• If you plan to drink alcohol, consider limiting the amount and avoid driving or operating machinery if you feel drowsy.

Other medicines

Progesterone is metabolised primarily in the liver. Medicines that influence liver enzymes may affect progesterone levels. Tell your healthcare professional (or pharmacist) about:

• Enzyme inducers (medicines that speed up metabolism)
• Enzyme inhibitors (medicines that slow metabolism)
• Medicines for epilepsy, tuberculosis, or certain fungal infections
• Some antibiotics and antiretrovirals used for HIV (depending on the specific drug)
• Other hormonal medicines (including oestrogen-containing treatments)
• Over-the-counter medicines and supplements, including herbal products (e.g., St John’s wort), which can interact.

Key point: Always check interactions with a pharmacist, especially if you start or stop any new medication.

Indications (What Prometrium is used to treat)

Prometrium is indicated for:

• Hormone replacement therapy regimens requiring a progestogen component to protect the uterus when oestrogen is used (where appropriate).
• Progesterone support in certain fertility and reproductive treatment plans, as determined by your healthcare team.
• Other uses where progesterone therapy is appropriate under clinical guidance.

Because indications depend on individual factors (such as whether you have a uterus and your treatment goals), it’s important to follow the specific plan provided to you.

Dosing: Typical Regimens (General Information)

Dose and schedule vary by indication, stage of treatment, and your health profile.

General guidance

• Follow the dose stated on your prescription/medicine label and any written treatment plan from your healthcare professional.
• Do not change the dose without medical advice.
• If you experience side effects, do not stop suddenly—contact a healthcare professional for advice.

Examples of commonly used dosing patterns

The following are general examples of patterns seen in clinical practice. Your exact dose should be confirmed from your treatment plan and medicine label.

• Endometrial protection with oestrogen: may be prescribed for a set number of days per cycle or as a continuous regimen, depending on your menopause/hormone therapy plan.
• Fertility support: dosing schedules can vary (often started at specific points relative to ovulation or embryo transfer).

Strengths and instructions: Prometrium capsules come in specific strengths (commonly 100 mg and 200 mg in many markets). Always confirm your strength and dosing frequency on your packaging.

Safety Profile: Who Should Be Careful

Most people tolerate progesterone reasonably well, but like all medicines it can cause side effects and may not be suitable for everyone.

Common side effects

• Drowsiness, tiredness, or feeling sleepy
• Dizziness
• Headache
• Nausea or stomach discomfort
• Bloating or breast tenderness
• Changes in mood
• Vaginal spotting or bleeding changes (especially when starting or changing hormone regimens)

Seek urgent medical help if you develop

• Signs of a blood clot such as sudden shortness of breath, chest pain, coughing blood, or one-sided leg swelling/pain
• Severe headache, vision changes, or weakness/numbness on one side
• Severe allergic reaction (e.g., swelling of face/lips, difficulty breathing, rash/hives)
• Yellowing of skin/eyes (jaundice) or severe abdominal pain (possible liver issues)

People who should discuss suitability with a healthcare professional

Discuss your medical history with a clinician/pharmacist if you have (or have had):

• Liver disease
• A history of hormone-related conditions
• Unexplained vaginal bleeding
• Known risk factors for thrombosis (blood clots)
• A history of depression or significant mood disorders

Practical advice: If you are already taking medicines affecting the risk of clots or you have cardiovascular risk factors, ask a professional for a tailored safety review.

Practical Use Tips

How to take Prometrium safely

• Swallow the capsule whole with water (do not crush unless your product instructions say otherwise).
• Choose a time you can keep consistently. If you feel sleepy, consider evening dosing.
• If you take other medicines, maintain spacing if your pharmacist recommends it.

What to expect when starting

• You may notice early side effects such as tiredness or mild nausea.
• Some bleeding changes can occur when adjusting hormone therapy, particularly at the beginning of treatment.
• It may take time to notice symptom improvement (depending on the reason you’re taking it).

Managing missed doses

Because schedules vary, the approach to missed doses may differ. As a general patient-friendly principle:

• If you miss a dose, check the leaflet and follow the missed-dose guidance.
• Do not double up unless instructed by your healthcare team.
• If you’re unsure, ask a pharmacist for advice using your dosing schedule details.

Monitoring and follow-up

Your clinician may monitor:

• Symptoms and side effects
• Bleeding patterns (in hormone therapy regimens)
• Appropriate investigations depending on your treatment goal (e.g., fertility monitoring)

Alternative Options

Depending on the reason for progesterone therapy, there may be other ways to achieve similar goals. Alternatives include:

• Other oral progestogens (different progesterone/progestogen formulations)
• Vaginal progesterone (often used in fertility settings in some protocols)
• Different hormone therapy regimens for menopause (including other progestogens or scheduling approaches)
• Non-hormonal symptom management for certain menopause symptoms, where appropriate

Important: Alternatives can have different side effect profiles, dosing schedules, and suitability. Discuss with a healthcare professional before switching.

Market and Legal Context for the UK

In the United Kingdom, hormone medicines such as Prometrium are regulated by the medicines framework administered through the relevant UK regulatory and health bodies. Supply is managed through appropriate channels and patient information is provided with each product.

UK pharmacy supply arrangements may vary depending on product availability and whether a medicine is classified as prescription-only or subject to other supply restrictions. Always follow the availability information shown on the product page and any guidance provided at checkout or with the medicine.

Recent guidance themes in the UK have focused on:

• Individual risk assessment when using hormone therapy
• Using the lowest effective dose for the shortest appropriate duration
• Monitoring unusual symptoms, particularly abnormal bleeding and vascular/cardiovascular symptoms

Clinical note: Decisions about hormone therapy should be personalised, taking into account age, time since menopause (if relevant), personal and family medical history, and thrombotic/cardiovascular risk.

Delivery and Availability (UK)

Availability and delivery timelines can vary between online pharmacies. Common expectations in the UK include:

• Standard delivery options (typically a few working days)
• Tracked delivery in many cases
• Order processing time before dispatch

Patient tip: Order early if you are following a strict treatment schedule (e.g., fertility protocols). If your delivery is delayed, contact customer support promptly so you can discuss options.

When you receive Prometrium, check:

• The strength on the label matches your plan
• The expiry date is valid
• The packaging is intact

Frequently Asked Questions (FAQ)

1) What is Prometrium used for?

Prometrium (micronised progesterone) is used to support hormone balance in specific situations—most commonly endometrial protection when used with oestrogen therapy, and progesterone support in certain fertility-related treatment plans, depending on your individual clinical plan.

2) How quickly will it start working?

Some hormone effects begin soon after absorption, but symptom improvement and cycle/bleeding changes may take time. If you’re using it as part of a fertility protocol, timing is critical to match your treatment schedule.

3) Can I take Prometrium with food?

In many cases, you can take it with or without food. If it upsets your stomach, taking it with a meal may help. Follow the advice in your product information and your clinician’s instructions.

4) Will Prometrium make me sleepy?

Some people feel drowsy or tired. If this happens to you, consider taking your capsule in the evening and avoid driving or operating machinery if you feel affected.

5) Can I drink alcohol while taking Prometrium?

Alcohol may increase dizziness or sleepiness. It’s best to avoid heavy drinking and be cautious if you feel drowsy. If you have concerns, ask your pharmacist.

6) What should I do if I miss a dose?

Because dosing schedules can differ, check the patient information leaflet for your regimen and follow the missed-dose guidance. In general, do not double up unless instructed. If you are unsure, contact a pharmacist.

7) Are there any serious side effects I should watch for?

Yes. Seek urgent medical help if you develop symptoms suggestive of a blood clot (such as sudden breathlessness, chest pain, or one-sided leg swelling), severe allergic reactions, or signs of liver problems (e.g., jaundice).

8) Can Prometrium be used if I have liver problems?

Liver health matters for many hormone medicines. Discuss your history with a clinician/pharmacist before starting or continuing therapy.

9) Can I use Prometrium for contraception?

Prometrium is not intended as a contraceptive. If you need contraception, use a suitable method recommended for your situation.

10) What are alternatives to Prometrium?

Alternatives may include other progesterone or progestogen formulations (oral or vaginal) or different hormone therapy regimens, depending on the goal. Your clinician/pharmacist can advise based on your indication and preference.

When to Contact a Healthcare Professional

Contact a healthcare professional promptly if you:

• Experience severe or worsening side effects
• Have unexpected heavy bleeding or unusual vaginal bleeding
• Develop symptoms of possible blood clots or severe allergic reactions
• Are unsure about dosing timing or missed doses
• Start a new medicine or herbal supplement and want to check interactions

Summary: Prometrium (progesterone) is a natural progesterone medicine used to support hormonal conditions—particularly endometrial protection with oestrogen therapy and progesterone support in reproductive treatment plans. It may cause sleepiness and other common effects, and—while generally well tolerated—requires attention to safety and potential interactions. Always follow the regimen provided with your medicine and seek professional advice for concerns.