Get emergency medical help if you have any of these signs of an allergic reaction to Generic for Bactrim DS: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

diarrhea that is watery or bloody;

fever, chills, swollen glands, body aches, flu symptoms, sores in your mouth and throat;

new or worsening cough;

pale skin, feeling light-headed, rapid heart rate, trouble concentrating;

easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

severe tingling or numbness, slow heart rate, weak pulse, muscle weakness;

nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

urinating less than usual or not at all;

hallucinations, seizure (convulsions);

low blood sugar (headache, hunger, weakness, sweating, confusion, irritability, or feeling jittery);

the first sign of any skin rash, no matter how mild; or

severe skin reaction -- fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Less serious Generic for Bactrim DS side effects may include:

vomiting;

painful or swollen tongue;

dizziness, spinning sensation;

ringing in your ears; or

tired feeling, sleep problems (insomnia).