As there is strong evidence that MS is of bacteriological etiology (Lida Mattman and other researchers),
I would assume that corticosteroids exacerbate MS and that CNS antibiotics like doxycycline cause a Jarish-Herxheimer reaction
(temporary exacerbation followed by improvement of symptoms).

According to Meyler's side effects of drugs, 14 th edition:

- There are two case reports of central nervous system demyelination after 6
weeks post administration in 2 patients with the HLA hyptotype for multiple
sclerosis (MS) after  administration of recombinant hepatitis B vaccine. One
of the patients was known with former diagnosted MS, the other patient had
no history of neurological diseases.
A casual link between hepatitis B vaccine and demyelination is not sure.

- There has been a hypothesis that there is a link between
glucocorticostero?ds and MS, but untill the year 2000 (year the 14th edition
has been printed) no unquestable proof has been found.

- After traement with interferon-gamma, exacerbation of MS has been
observed.

Greetings,
Jos