Thank you for choosing ATD.
Here is a list of some of the common side effects of Sulfamethoxazole-Trimethoprim:
Reaction due to an Allergy
Loss of Appetite
As you can see, the above have in the list headaches and sun-sensitive skin. The sun sensitive skin could lead to rash on the back of the head due to sunburn while you are out in the sun.
This could cause the red spot at the back of the head. These are not permanent side effects and will wear off soon after you stop taking the medication.
I hope this helps you. All the best.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.