Starting HRT often comes with an uncomfortable middle stretch: the symptoms that prompted the decision may not have improved yet, and new ones have appeared. At four to six weeks, many women wonder whether to continue. Most should.

The first three months are an adjustment period. Understanding what is normal during that window (and what warrants an earlier call to your prescriber) makes it easier to stay the course when you should, and to act when you need to.

The Three-Month Evaluation Window

NICE, NAMS, and BMS all frame the first three months as the adjustment period.[1] Side effects in this window are largely the body adapting to a new hormonal environment, not signals that HRT is wrong for you; a follow-up at around twelve weeks is standard to review symptom relief, assess side effects, and make any dose or formulation adjustments.[2]

Decisions about whether HRT is working should not generally be made in the first four weeks. Stopping because of initial side effects that would have resolved by week six is common and often avoidable.

Expected Side Effects and Their Timelines

Breast tenderness

Breast tenderness affects approximately 29% of women starting HRT.[1] It presents as general sensitivity or fullness, sometimes worse in the weeks before the progestogen phase on cyclical regimens. For most women it resolves within two to three months. A supportive bra and reduced caffeine can help in the interim.

If tenderness is severe, persists beyond three months, or is accompanied by a palpable lump or nipple changes, seek clinical review.

Bloating and nausea

Bloating and nausea are more common with oral estrogen than with transdermal preparations, because oral estrogen passes through the liver increasing bile acid production.[1] Switching to a patch, gel, or spray often resolves them entirely. They rarely persist beyond six weeks even without changing formulation.

Breakthrough bleeding

Breakthrough bleeding (any vaginal bleeding outside a scheduled withdrawal bleed on a cyclical regimen) is common during the first three months.[2][3] For women on continuous-combined HRT (designed to produce no periods), irregular bleeding is expected initially as the endometrium adjusts to continuous progestogen. By twelve months, approximately 90% of women on this regimen have no bleeding, based on data from Panay & Fenton (2012)[3], a figure that aligns with current clinical experience though it awaits replication in a more recent large cohort.

Breakthrough bleeding warrants investigation if it: - Persists beyond six months of continuous-combined HRT - Occurs after a settled period of no bleeding - Is heavy, with clots, or accompanied by pain

Irregular bleeding in the first three months does not by itself indicate a problem.

Headaches

Headaches are more common with oral estrogen, which creates fluctuating peaks and troughs with each dose. Women who already experience hormonal migraines may find oral HRT worsens them. Transdermal estrogen provides more stable levels and is better tolerated in migraine-prone women.[1][2]

If headaches begin or worsen after starting HRT, switch to transdermal delivery before concluding that HRT itself is the issue.

Mood changes and PMT-like symptoms

Some women experience irritability or PMT-like symptoms in the early weeks, particularly on cyclical progestogen regimens.[1] Synthetic progestins (norethisterone and medroxyprogesterone acetate) cause mood symptoms more often than micronized progesterone (Utrogestan, Prometrium). If mood symptoms are a significant problem and you are on a synthetic progestin, discussing a switch to micronized progesterone is a reasonable step at the three-month review.

For women starting HRT primarily for mood, benefits take longer to appear than vasomotor benefits. Improvement in the first two weeks is unlikely; change by three to four months is a realistic benchmark.

When Symptoms Don't Improve

The most common reason HRT fails to relieve symptoms adequately in the first three months is dose, not suitability. Starting doses are intentionally conservative, and many women need an increase to achieve symptom control.[2]

Symptom response also differs by type:

Vasomotor symptoms (hot flashes, night sweats) often begin to improve within two to four weeks of reaching an effective dose.

Sleep tends to improve alongside vasomotor symptoms, since night sweats are a primary disruptor. Changes to sleep architecture independent of vasomotor symptoms may take longer.

Genitourinary symptoms (vaginal dryness, discomfort) from GSM respond more slowly to systemic HRT and often require local vaginal estrogen as an additional or alternative treatment.

Mood and cognitive symptoms generally take the longest, often eight to twelve weeks or more, as they depend on hormonal stabilisation that builds gradually.

Preparing for the Three-Month Review

The three-month appointment is when adjustments get made. It helps to arrive with:

  • A note of which symptoms have improved and by how much
  • A log of any side effects and how they changed over time
  • Details of any breakthrough bleeding and its pattern
  • Any new symptoms that appeared after starting

This review is the primary opportunity to adjust dose or formulation; arriving prepared makes it more productive. If your prescriber does not offer a proactive three-month review, request one.

References

[1] Levy, R. L., De Silva, P. S. A., et al. (2023). Prescribing hormone replacement therapy: Key considerations for primary care physicians. Canadian Family Physician, 69. https://pmc.ncbi.nlm.nih.gov/articles/PMC10325598/

[2] Dempsey, M., Freedman, M. (2019). Hormone therapy for first-line management of menopausal symptoms: Practical recommendations. Obstetrics and Gynecology Clinics of North America, 46(3). https://pmc.ncbi.nlm.nih.gov/articles/PMC6683316/

[3] Panay, N., Fenton, A. (2012). Hormone replacement therapy: Indications and side effects. Obstetrics, Gynaecology and Reproductive Medicine, 22(7). https://pmc.ncbi.nlm.nih.gov/articles/PMC3300449/