Do you always get a fever when you get blood poisoning?

Not necessarily: You usually get a fever with blood poisoning but oftentimes you don't, esp when you have an overwhelming infection which suppresses your immune system so you cannot mount the fever, or you are immunosuppressed to begin with - cancer, chemotherapy, aids, renal failure, immunosuppressive medications to name a few.

Usually: Blood poisoning is a lay term for lymphangitis. Lymphangitis is an infection of the lymphatic channels in the subcutaneous tissue. It usually occurs on an extremity. It is usually caused by beta hemolytic strains of streptococci and occasionally by staphylococcus aureus or p. Multocida after a cat bite. Fever is frequently but not always present.