Categorize the ailments into different disorder groups.
Ailments: headaches, nausea, dizziness, allergic reactions
Disorder Groups:
1. Neurological disorders - headaches, dizziness
2. Gastrointestinal disorders - nausea
3. Immunological disorders - allergic reactions
Complete the following task based on the instruction and optional input provided.### Instruction:
Categorize the ailments into different disorder groups.

### Input:
Ailments: headaches, nausea, dizziness, allergic reactions

### Output:
Disorder Groups:
1. Neurological disorders - headaches, dizziness
2. Gastrointestinal disorders - nausea
3. Immunological disorders - allergic reactions