My rheum suggested Plaquenil for the fatigue.
Can it affect the SFN and POTS ? can it make it worse ?

Plaquenil has been reported to cause nerve damage.

Here is one example from New Zealand;
Risks of Hydroxychloroquine

If you Google further you will find more I think.

Plaquenil has a quinolone central nucleus making it a cousin of the fluoroquinolone antibiotics, which cause PN in some patients.

Thanks!
I will read the link that you sent.
I tried to do too much this week and I'm too exhausted and brain fogged to read it thoroughly right now.

Plaquenil is well known to help fatigue associated with autoimmune disease.

Although I have never heard of neuropathy caused by its use, the article does say there was two reported cases in New Zealand. However, there are thousands that take it, so the risk must be very low.

That being said, it is imperative to have regular (every 6-12 months) checks by an ophthalmologist for toxicity associated with retinal damage (which can be permanent if not caught early). I have taken Plaquenil for 8 years now and still go every 6 months for eye exams and use a chart every WEEK to check for any signs of vision changes.

As ll medications, you have to weigh the risks vs the benefits.

Thanks MrsD and en_block!
I will take into consideration those risks.
en_block, can you do the weekly test yourself at home ?

I'm getting Rituximab and it is helping a lot, the problem is that I can take it only in 6 months interval, while its effect lasting only 2-3 months, so this year has been a roller coaster...
The neuro said the effect is cumulative, so gradually it might get longer.
The rheum suggested the plaquenil to help the fatigue in the meantime, so I'm considering giving it a chance. It is challenging (impossible?) to return to work when 6-8months a year it is difficult to get out of bed and my brain is on a strike.

My SFN and POTS are probably caused by autoimmune disease, if plaquenil is considered a disease modifier drug, can it help with the SFN, POTS?

If you decide to try Plaquenil, check out the list of drugs to avoid that are listed here:

Common Side Effects of Plaquenil (Hydroxychloroquine) Drug Center - RxList

It is interesting to note, that the brand name has been discontinued this year, and only generic is available now.

Drug companies often discontinue their brand name, or sell it when sales are low, and/or they have too many liability suits for damages to settle. When a drug causes damages to people, the liability falls to the patent holder and it is common for the patent holder to discontinue that drug when it can no longer make $$ from it.

Plaquenil has many serious side effects, which are listed on that page as well. So be very careful and monitor yourself for any of these side effects.