@cheshirecatssmile From the link -
Does HRT interact with my epilepsy medicines?
Certain antiepileptic drugs can interact with HRT, reducing the level of hormones which makes the HRT less effective in the usual doses.
You can still take HRT, but you may need a slightly higher dose of HRT to relieve your menopause symptoms.
Drugs that can reduce the effects of HRT include carbamazepine, cenobamate, eslicarbazepine, fosphenytoin, oxcarbazepine, perampanel, phenobarbital, phenytoin, primidone, rufinamide and topiramate. This effect is more likely with oral HRT than transdermal.
Antiepileptic drugs that do not affect HRT include brivacetam, clonazepam, ethosuximide, fenfluramine, gabapentin, lacosamide, lamotrigine, levetiracetam, piracetam, pregabalin, tiagabine, sodium valproate, stiripentol, vigabatrin and zonisamide. This list is not exhaustive, and you should check with your healthcare professional about potential interactions between HRT and your antiepileptic medication.
A note about lamotrigine Although lamotrigine does not affect the levels of HRT, HRT can decrease blood levels of lamotrigine. This is important if you are already taking lamotrigine when you start HRT, as it may result in poorer epilepsy control. This does not mean that you can’t take HRT if you are taking lamotrigine – a small adjustment to the lamotrigine dose is all that is needed. There is no problem starting lamotrigine if you are already taking HRT as the dose of lamotrigine will be adjusted to provide the best seizure control. In both cases, if you stop HRT, the lamotrigine dose may need to be slightly reduced.
So, can I take HRT if I have epilepsy?
If you have menopause symptoms that might benefit from HRT, epilepsy is not a reason to avoid HRT. To minimise any potential adverse effects of HRT on epilepsy, transdermal estrogen is recommended, together with body identical progesterone. You should start with a low dose and increase the dose until you reach the lowest dose that controls your menopause symptoms.