What makes our sweat smelly?

Dear doc, I have two questions; I experience a bad odour wherever I sweat, mostly after sexual intercourse, what could be the problem? My umbilicus has been aching from the inside for a while now, what could be the problem? Betty Dear Betty,The bad smell from your body or body odour is known as bromhidrosis. Everyone has body odour and it occurs due to the bacteria on the skin breaking down the acids in the sweat. It becomes significant after puberty due to development of the apocrine sweat glands. Men tend to have worse body odour than women because they tend to sweat more. If you sweat excessively, you may have more body odour, especially in the feet or armpits. The sweating can also affect the natural smell from the vulva.Body odour can be worse if you are obese; you take alcohol, spicy foods or garlic; if you are taking some medications such as antidepressants or if you have some illnesses like diabetes, liver disease, kidney disease and some cancers. There is a rare genetic disorder called trimethylaminuria that causes someone to have a fishy odour. To manage the body odour, shower daily and if possible twice a day on hot days; wash your armpits thoroughly, if possible, with antibacterial soap; shave your armpits regularly so that the sweat evaporates faster; dry yourself thoroughly with a clean towel; wear clean clothes and socks made of natural fibres like cotton, silk, wool; use a strong underarm anti-perspirant/deodorant; use deodorant foot powder; wear open shoes or go barefoot as much as you can; use a pumice stone to clean off dead skin on the soles of the feet and limit the amount of spices, onions, garlic, red meat, coffee and alcohol you consume.You can also apply aluminium chloride solutions or 0.5 per cent glycopyrolate solution on your armpits and feet, preferably in the evening just as you are going to sleep to reduce how much you sweat the following day. Some other procedures that can be done to the most affected areas include iontophoresis, which utilises an electric current that is run through the skin; use of anticholinergic medication; or by intra-dermal injection with botulinum. These should be done by a skin specialist (dermatologist). In severe cases, surgery may be done.The vagina has a normal musty smell, which changes due to hormonal changes at different times of the monthly cycle or due to pregnancy, menopause or use of hormonal medications. The odour may also be different after intercourse due to mixing with semen and/or a lubricant. Some women experience a metallic smell during periods due to the iron in the blood. A change in the odour can also happen due to sweating a lot or due to taking foods or drinks that have strong smells like garlic, onions, caffeine and some fruits. These changes do not require treatment. For odour changes associated with intercourse, cleaning up before and after may reduce the smell.If, in addition to the odour you have itching or an abnormal discharge, or low abdominal pain, then most likely you have an infection, and it would be advisable to see a doctor so that you can have tests done to get an accurate diagnosis and you will be put on the appropriate treatment.The umbilicus and the area around it can have pain due to a variety of issues. To begin with, the umbilicus itself may have pain resulting from injury, infection or friction, and there may also be bleeding, discharge, foul smell, itching or change in colour. This is treated with ointments or antibiotics depending on the cause.Pain at or around the umbilicus may also be due to an umbilical hernia, where a small part of the abdominal contents protrudes through a weakening in the abdominal wall at the umbilicus. In this case, there is a swelling that becomes bigger and/or more painful when one coughs or lifts something. This requires surgery to correct. There can also be pain in or around the umbilicus due to problems within the abdomen and pelvis, for example indigestion, bloating, constipation, infection or inflammation of the intestines, ulcers, gall stones, appendicitis, urinary tract infection or inflammation of the pancreas. You may also have umbilical pain around the time of your periods if you have some displaced endometrial tissue attached to the umbilicus due to endometriosis. Pregnancy may also be associated with umbilical pain.It is advisable for you to see a doctor for examination and relevant tests based on the findings. Treatment will depend on the underlying cause. Hey Doc,I have been having a black streak line in my thumb fingernail for about a year now. What could be the underlying cause?SimonDear Simon,You can get a black streak due to bleeding under the nail as a result of injury or if you are taking blood thinning medication. You can also get a dark line as a result of other health conditions including kidney disease, lung disease, problems with blood circulation or endocarditis (infection of the inner lining of the heart).You may also have melanonychia, darkening caused either by activation of melanocytes (cells that produce the pigment melanin) or by increase in the number of melanocytes.The melanocytes can be activated due to genetics (higher incidence of streaks in people from dark-skinned races), pregnancy, poor nutrition, infections, inflammatory diseases, systemic illnesses, injury, medication such as chemotherapy, HIV medication and some malaria medications.Where there is increased multiplication of the melanocytes, it may be non-cancerous such as where there is a mole; or it may be cancerous, and a sample of the tissue needs to be taken to determine which it is.Most of the time, depending on the underlying cause, the darkening of the nail may be harmless and not require any treatment. Where treatment is needed, it will depend on the cause.Send your health questions to [email protected]