Can a patient with allergy reaction towards Ibuprofen use Ketoprofen patch?

To answer this question, we must first know that there are specifically 2 types of allergy reactions when NSAIDs are involved:

a)Pseudoallergic NSAIDs reaction

b) Allergic NSAIDs reaction

Pseudoallergic NSAIDs Reaction

Pseudoallergic reactions are elicited by any cyclooxygenase (COX)-1 inhibiting nonsteroidal antiinflammatory drug (NSAID), and the likelihood that an NSAID will cause these in a susceptible patient is related to the strength with which that drug inhibits COX-1. Pseudoallergic reactions are usually seen in patients with one of the following comorbidities: the combination of asthma and chronic rhinosinusitis with nasal polyposis; or chronic urticaria.

Allergic NSAIDs Reaction (Presumed IgE Mediated Reaction)

Allergic reactions to nonsteroidal antiinflammatory drugs (NSAIDs) range from urticaria/angioedema to life-threatening anaphylaxis. In contrast to pseudoallergic reactions, these reactions are elicited by a single NSAID, or rarely by more than one agent with similar molecular structures. Patients with allergic reactions to an NSAID have had at least one prior exposure to the culprit drug, which presumedly sensitizes them and results in symptoms upon repeat exposure to the same drug [10,11].

These reactions are believed to be IgE-mediated, and the allergen is thought to be a drug metabolite bound to a carrier protein. In the United States, most of these reactions have been associated with Ibuprofen,  although they can happen with any NSAID. However, at present, there are no practical or commercially available tests to detect IgE to NSAIDs (such as skin testing or drug-specific serum IgE tests).

Hence to answer this question, if the types of NSAID allergy is not identified, it is recommended to avoid all types of NSAIDs.

References:

1. Simon RA. NSAIDs: allergic and pseudoallergic reaction.  UpToDate Inc. Available at: http://www.uptodate.com.ezp.imu.edu.my/contents/nsaids-including-aspirin-allergic-and-pseudoallergic-reactions?source=search_result&search=cross+allergy+nsaids&selectedTitle=1~150