How often is too often for re-wetting drops?

Two regimes:

• Preservative-free unidose vials: use freely, every 30–60 minutes if needed. Each vial is good for one day (some are good only for 12 hours after opening).
• Multi-use bottles with preservatives: limit to ~4 drops per eye per day. The preservatives are gentle but cumulative use can irritate sensitive corneas.

If you find yourself reaching for drops every 30–60 minutes routinely, the underlying cause likely needs addressing rather than more drops:

• Lens material may not suit your tear film.
• Environment (heating, air-conditioning, screens) may be drying.
• You may have undiagnosed dry-eye disease worth investigating.

Persistent need for hourly drops is a sign to book an optician check.