NEW YORK (AP) _ American Home Products Corp. is considering whether to appeal a federal judge's decision allowing a rival to sell ibuprofen tablets that are the same color as American Home's Advil ibuprofen pain reliever.

Carol Emerling, a spokeswoman for American Home, said Thursday that the company has not yet decided whether to appeal the March 23 decision by Judge Harold Ackerman of U.S. District Court in Newark, N.J.

The judge's decision could be important for the growing number of companies who use color as a marketing tool.

American Home filed the suit last year against L. Perrigo Co., an Allegan, Mich.-based subsidiary of Grow Group Inc. that makes and distributes lower- priced health and beauty items for sale under store labels.

The New York-based American Home told the court it had spent more than $100 million advertising its Advil tablets and said its distinctive brown color was a key element in the brand's image, identifying Advil for many consumers.

In a telephone interview Thursday, Michael Jandernoa, Perrigo's president, said his company made its ibuprofen tablets brown because its studies showed consumers felt a brown color ''improves the effectiveness of the product.''

But he said consumers were unlikely to confuse the products in stores because the packaging was quite dissimilar.

Judge Ackerman sided with Perrigo, denying American Home's request for an order halting the sale of its competitor's brown ibuprofen tablets.

He said Perrigo's tablets resembled an ''old aspirin tablet painted Advil brown,'' a striking contrast with ''sleek, modern Advil.'' The judge wrote that two tablets ''are clearly dissimilar in overall appearance.''

Marketing consultants say color has become a more important consideration as competition for the consumer's attention has intensified.

''Consumers don't read that well, and when they see a package that resembles what they have been buying, they just pick it up,'' said Fred Mittleman, a partner in the consulting firm Mittleman-Robinson Design Associates in New York.

He said color and packaging have become so important to some companies that they have sought to register them to protect against imitation.

In October 1985, Owens Corning Fiberglas Corp. won a court order that it be given the exclusive use of the color pink for home insulation.

But Charles Condro, administrator for trademark policy and procedure for the U.S. Patent and Trademark Office in Arlington, Va., said that case was very unusual.

He said in most cases colors are not trademarked because they are functional - mint green for mouthwash, for instance, or yellow for antifreeze - or because granting an exclusive right to a color would inhibit competition.

Gerron Vartan, senior vice president for S&O Consultants Inc. in San Francisco, said companies who want to be identified with a color must use it ''aboslutely consistently'' in everything they do and be vigilant and vocal about any other company's effort to copy it.