“What is the best medicine for dry eyes?”

There are certainly over-the-counter artificial tears for dry eyes, and there are prescription medications that require a doctor's advice, consent, and written prescription. Warm compresses and eye lid scrubs may help dry eye conditions. And some of the dry eye medications include restasis, Xiidra, cequa, eysuvis, lacrisert, and OTC dry eye drops such as Visine Red Eye Comfort and Clear Eyes Red Eye Comfort drops.
If your eyes are itchy, eye drops such as Pataday or Zatidor can relieve the itchiness. But what needs to be determined is do you have a dry eye problem or an allergy problem that can be causing the itchiness? Only an eye doctor or your family doctor should determine that fact.
A few studies have shown that omega-3 fatty acid supplements may improve symptoms of dry eye. But these should only be taken with the consultation with your family doctor or your eye doctor, always. Punctal plugs can be inserted into the eye's puncta in order to keep the tears within the eye for longer periods of time, again, under the care of an eye doctor.
So, if you know that you have dry eyes, was this diagnosed by a doctor? My best recommendation is to see that doctor or any eye doctor. Some of the anti-redness or decongestants can cause a glaucoma problem in those people who have narrow angles, so I would not self-medicate until you know exactly what the problem is, and how to effectively and to properly treat it. Good luck and best wishes.

Drink more water , wash eyes with warm water and use artificial tears twice aday . All brands are good

depends of the cause of the dryness

Lots ! Systane, refresh , etc

Dry eyes can be treated with over the counter lubricating drops.