Irvine-based drug maker Allergan Inc.’s long-term debt ratings have been raised by Fitch Ratings Inc.

Fitch said it upgraded the maker of Botox and other drugs for several reasons, including being “unscathed by the global recession,” manageable European exposure, maintaining strong liquidity and taming of shareholder pressures.

The rating agency raised Allergan’s debt ratings to “A+” from “A,” both of which are investment-grade. Fitch also affirmed its stable outlook for Allergan and affirmed its short-term debt ratings at “F1,” indicating a strong capacity to meet financial commitments.

Allergan’s revenue grew 10% to $5.4 billion last year.

Fitch said that Allergan’s body and facial aesthetic products have proven to be resilient to economic uncertainties. Both represent big portions of Allergan’s cash-pay businesses, which make up some 40% of the company’s revenue.

The ratings, which apply to about $1.6 billion of outstanding debt, allow Allergan to borrow money at a lower rate.