HRT side effects: the first weeks, honestly

Usually settle on their own

These are common in the first weeks as your body adjusts to a hormone it has not had steady levels of for a while:

• Breast tenderness or swelling
• Nausea, often better if oral medication is taken with food or at night
• Headaches
• Bloating
• Leg cramps
• Mood swings in the first few weeks
• Irregular bleeding or spotting, particularly in the first three to six months on a continuous regime
• Skin irritation at a patch site, which usually resolves by rotating sites properly

The reasonable window is around three months. If something is still bothering you at that point, it is not "just settling" any more and it is worth raising.

Usually mean the dose or format needs adjusting

• Breast tenderness that persists past three months, which can indicate the oestrogen dose is higher than you need
• Ongoing nausea on an oral preparation, where switching route often solves it
• Persistent bloating or mood effects that track with the progesterone part of the regime, where the type, dose or timing can often be changed
• Symptoms that never improved at all, which more often means the dose is too low than that HRT does not work for you
• Repeated skin reactions despite rotating sites, where a different format is the answer

Needing an adjustment is normal. Most women fine-tune once or twice in the first months. At fira, dose changes are reviewed by a clinician and there is no charge for them.

Speak to a clinician promptly

• Unexpected or heavy vaginal bleeding, particularly if it starts after a settled period on treatment, or continues past six months on a continuous regime
• Any bleeding after menopause that was not expected on your regime. See bleeding after menopause, which needs a doctor rather than a dose change
• A new or markedly worse headache, particularly with visual symptoms. Speak to a clinician the same day
• Yellowing of the skin or the whites of the eyes. Same-day advice
• Blood pressure that has risen

A new breast lump is not a side effect of HRT. It is not on this list because it is not something to adjust a dose for. Any new lump, change in breast shape or skin, or nipple change needs a GP appointment this week.

Seek urgent medical attention

These are uncommon, and they are the reason the list exists:

• Sudden breathlessness or chest pain
• Coughing up blood
• Sudden severe headache, weakness or numbness on one side, drooping of the face, or difficulty speaking
• Sudden vision loss
• Swelling of the face, lips or throat, or difficulty breathing, which can indicate a severe allergic reaction

Call 999 now for any of the above. Do not wait for a routine appointment and do not drive yourself.

• Pain, swelling, redness or heat in one calf

For a suspected clot in the leg without any of the chest or breathing symptoms above, seek urgent same-day medical advice. Call 111 if you are not sure which applies to you.

What is not a side effect

Weight gain. This is the most common reason women give for not starting HRT, and the evidence does not support HRT itself causing weight gain. Weight tends to change around menopause regardless, with a shift toward the middle driven by falling oestrogen and ageing. Fluid retention in the early weeks can look like weight gain and usually settles.

The route changes the risk profile

Not all side effects and risks are equal across formats. Oestrogen taken by mouth passes through the liver and affects clotting factors; oestrogen through the skin does not, and is not associated with the same clot risk. UK guidance recommends the transdermal route for women at increased risk of VTE.

The type of progestogen matters too. A meta-analysis has found oestrogen combined with micronised progesterone is not associated with increased breast cancer risk in the first five years.

Reporting side effects

Suspected side effects of any medicine can be reported to the MHRA through the Yellow Card scheme, by you as well as by a clinician. Reporting is how signals get spotted.