Antihistamines are not helpful

Options

A. in curing nasal allergies
B. in treating rashes caused by itching
C. in bringing down acute fever
D. in vasodilation

Explanation

### Step-by-Step Solution:

1. **Understanding Antihistamines**:
- Antihistamines are a class of drugs that block the action of histamine, a substance in the body that causes allergic symptoms. They are commonly used to alleviate symptoms associated with allergies.

2. **Identifying Uses of Antihistamines**:
- Antihistamines are effective in treating:
- Itching and rashes caused by allergic reactions.
- Nasal allergies, which include symptoms like sneezing and runny nose.
- Vasodilation, which is the widening of blood vessels.

3. **Analyzing the Options**:
- The question asks in which condition antihistamines are not helpful.
- We need to evaluate the options provided to determine the correct answer.

4. **Evaluating Each Option**:
- **Option 1**: Antihistamines are helpful in treating itching and rashes.
- **Option 2**: Antihistamines are helpful in treating nasal allergies.
- **Option 3**: Antihistamines are not helpful in bringing down acute fever.
- **Option 4**: Antihistamines can help in vasodilation.

5. **Conclusion**:
- From the evaluation, it is clear that antihistamines are not effective in treating acute fever. Therefore, the correct answer is **Option 3**.

### Final Answer:
Antihistamines are not helpful in bringing down acute fever.

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