This page provides and overview to some of the most common sexually transmitted infections. For information on testing, please see STI Testing. For information on preventing the transmission of STIs, please see Safer Sex. There are three types of STIs: viral, bacterial, and infestations.

Viral Infections


  • Symptoms: depressed immune functioning, fatigue, muscle pain, sore throat, fever (may or may not be present)
  • Transmission: unprotected vaginal/anal/oral sex, sharing of needles
  • Detection: specific blood test done 3 months after possible infection
  • Prevention: regular testing, always using condoms with water-based lubricant during sexual activity
  • Note: using spermicides may increase risk because they cause microtears in the vagina or anus, increasing the risk of infection.
  • No cure/vaccine
  • Extensive treatment options available

Herpes (simplex 1 and 2)

  • Transmitted through contact; viruses affect mouth/genital region
  • Symptoms: painful, itchy, fluid-filled sores inside/outside mouth or genitals; virus can spread when sores are not present. Note: canker sores are not herpes.
  • Prevention: regular testing, using condoms help reduce risk. Note: condoms may not fully prevent due to lack of coverage of testes and labia
  • Detection: medical physical exam if sores are visible; blood test to detect the strain
  • No cure, chronic/severe infections treated with anti-viral medication

Human Papilloma Virus (HPV)

  • Transmission: skin to skin contact
  • Symptoms: warts outside/inside genitals, warts vary greatly in appearance (smooth/bumpy/soft/ hard/white/skin colour/ possibly itchy).
  • Note: there are different strains of HPV, not all cause symptoms or venereal warts, but some cause cancer
  • Gardasil is a vaccine offered to young women to prevent cervical cancer caused by HPV; it is administered in 3 shots over 6 months
  • Detection: medical physical examination, females must have pap smear to detect abnormal cervical cells
  • Prevention: STI testing, use barrier methods, NOTE: condoms may not fully prevent due to lack of coverage of labia and testes
  • No cure. Treatment includes burning, freezing, laser therapy

Hepatitis B

  • Transmitted through vaginal, anal intercourse, oral-anal contact, needle sharing
  • Nausea, fatigue, jaundice, dark urine, generally feeling unwell, detected by blood test
  • No cure, just treatment, but vaccinations available
  • Detected by blood test

Hepatitis C

  • Transmitted through contact with bodily fluids
  • Symptoms: dark urine, abdominal pain, nausea
  • Detected by blood test, can be treated with antiviral medication, vaccine available

Bacterial Infections


  • Transmitted through contact
  • Males: urethral discharge; females: spotting, itching, burning sensation in genitals
  • Detected by swab or urine test for females and urine tests for males, treated with antibiotics


  • Transmitted through vaginal, anal, oral sex
  • Symptoms: thick discharge, painful urination, itching/burning genitals, sore throat if infection is oral, bloody stools and anal discharge if infection is anal
  • Detected by swab tests or urine tests with females and urine tests for males, treated with antibiotics


  • Transmitted through broken mucous membranes (vaginal, anal)
  • Symptoms: stage 1 – painless sore on infected area, stage 2 – flu-like symptoms, rashes, stage 3 – heart disease, paralysis, insanity
  • Detected with a specific blood test, treated with antibiotics

Cystitis (a.k.a. Urinary Tract Infection – UTI)

  • Bacterial infection of the urinary tract
  • Symptoms: frequent urination, painful urination, lower back/ lower abdominal pain, pain during vaginal intercourse
  • Detected by a urine test, treated with antibiotics

Vaginitis (bacterial and yeast infections)

  • Overgrowth of bacteria/yeast and can be transmitted through contact
  • Abnormal discharge, itching or burning
  • Detected by swab tests, treated with antibiotics/medication (natural methods such as inserting plain yogurt with tampon)
  • Prevention: peeing after sex, wiping front to back


Pubic Lice (Crabs)

  • Transmitted through skin-to-skin contact
  • Itchiness, bluish spots around genitals/thighs, live crabs are dark grey to red-brown in colour
  • Detected by physical exam, treated with medicated creams/shampoos, important to wash bedding, clothing, towels, etc.


  • Mites get under skin and lay eggs
  • Transmitted through contact, mites prefer warm moist areas
  • Itchiness, irritation
  • Detected by physical exam, treated with medicated creams

Fungal infections
While not technically STIs, this infection can be passed through sexual contact or by sharing sex toys.

Yeast Infection (Candida)
A vaginal yeast infection is a common fungal infection caused by overgrowth of Candida, naturally occurring yeast. Yeast is normally found in a woman’s vagina in small numbers, but sometimes they can multiply and change the normal balance of bacterial growth. When the fungi begin to grow in excess, they may develop into candidiasis.