There have been articles circulating on FB about both of these, and I've been asked about them.
Ibuprofen
Ibuprofen is an NSAID, or non-steroidal anti-inflammatory drug. It is known to reduce levels of IL-6, the inflammatory cytokine that is elevated in severe cases of covid-19 (more here). So you'd think it would actually help prevent severe symptoms, as the anti-IL6 drug Actemra does. This is also theoretically the mechanism of action of chloroquine and derivatives. It reduces IL-6 levels and therefore the severe inflammation that threatens to kill the patient.
But one doctor in France observed four young covid-19 patients whose symptoms worsened after taking ibuprofen, and raised an alarm. It is entirely possible that they would have worsened without ibuprofen. At this point, we have no controlled trials of any kind on this question. We just don't know.
On one hand, it doesn't make a lot of sense that an anti-inflammatory would worsen a disease that appears to cause an over-reaction of the immune system. On the other hand, there have been rare but real cases of bad reactions in children given aspirin (another NSAID) for fevers.
At this point, the French Minister of Health is recommending against NSAIDs for fevers, but the European Medicines Agency has put out a press release stating "There is currently no scientific evidence establishing a link between ibuprofen and worsening of COVID‑19. EMA is monitoring the situation closely and will review any new information that becomes available on this issue in the context of the pandemic."
So the short answer is that we don't know.
Elderberry
Elderberry / Sambucus syrup has been sold as an alternative treatment for the flu for many years. I first became aware of it when I as in grad school and researching flu. Someone gave me a bottle and asked me to test it to see if it interfered with flu's ability to infect cells. I did and it didn't. But the claim of at least some proponents of taking sambucus for flu is not so much that it blocks infection directly, but raises the immune response, which then fights off the flu.
This is at least plausible, but by no means certain. There is at least one report that human immune cells produce increased levels of IL-6 and other pro-inflammatory cytokines when they are removed from the body and exposed to sambucus syrup.
Given that severe cases of covid-19 have elevated IL-6, it makes sense to avoid sambucus/elderberry if you think that you might have the virus. However, there have been no reports of adverse reactions to elderberry in actual covid-19 patients.
