Men trying to keep several wives happy and women competing with co-wives for their husbands' attentions has led to a boom in the sale of herbal aphrodisiacs in predominantly Muslim northern Nigeria.
"Demand for sex stimulants has been unprecedented in the last four years," herbalist Sule Adamu told AFP in his dingy office on the outskirts of Kano.
Adamu, who has 40 years in the business, reckons his clients, mostly men, have more than tripled in number since 2005.
Women not satisfied with their husband's sexual performance also come for the drugs if their husbands are embarrassed to do so.
"Women also go for aphrodisiacs to make them appealing to their husbands. Mothers provide sex stimulants to their newly-wed daughters to aid them satisfy their grooms' sexual desires, said Hafsat Musa Baba of Kano-based Sustainable Development Centre (SUDIC), a reproductive health NGO.
Talatu Jatau, 53, has been selling aphrodisiacs for women, known simply as "women's stuff", in Kano for six years and makes a good living from it.
Every other month, she brings a bag-load of "women's stuff" from Zamfara state, 400 kilometres (250 miles) away and sells it in less than a week to women in purdah.
Lami Bello, 28, has been using women's herbal sex stimulants since she met her boyfriend three years ago.
"I have a very virile boyfriend who is so affectionate that I don't want to lose him. I realised the only way to keep him to myself is to satisfy his sexual urge; that is why I use aphrodisiacs and the experience has been worthwhile," she said with a smile.
Herbal aphrodisiacs are displayed everywhere in this city of some four million - in markets, bus stations, offices and even outside mosques.
Itinerant vendors advertise their wares using megaphones and loudspeakers hoisted on car roofs or on two-wheeler carts.
The drugs come in all forms - liquid, jelly and powder and are taken orally or rubbed on the penis.
The recipes are handed down from father to son and are a jealously guarded secret.
Haruna Usman, 39, has been using herbal stimulants for five years and says his sex life has greatly improved over that period.
Husband must prove 'manliness' to keep peace with wives.
"Before I began using the herbs I could only make love to my wife once a week due to low libido but now I make love not less than five times a week. And each time we do it three or four times over," he said.
"People have the notion that manliness is gauged by how sexually virile a man is, which explains the increase in the demand for sex improving drugs", said Mairo Bello of Adolescent Health and Information Project (AHIP), a Kano-based NGO.
Being a conservative Islamic society, Kano is largely polygamous with men taking as many as four wives, the maximum Islam allows.
With the wives competing for affection, the husband must prove his "manliness" to each of them to maintain peace in the home, SUDIC's Baba said.
Conventional aphrodisiacs such as Viagra, Cialis and Levitra are available in big drugstores in the city but many people prefer the herbs which are cheaper. A four-tablet pack of Viagra costs 27 dollars while a handful of herbs which lasts the user several days costs no more than two dollars.
Although users of local sex stimulants believe they are safer because they are herbal, side effects from sustained erection still occur in many cases.
Adamu concedes some of his clients come back to him with prolonged erection after using the aphrodisiacs, but says he treats the condition with a dose of herbal antidote.
Abubakar Abdullahi, a consultant urologist, says the prolonged erection side effect can do lasting damage.
"Half of those who experience this side effect become impotent once the erection subsides with or without medication," said Abdullahi, who has handled several such cases.
For the moment traditional medicine is not regulated anywhere in Nigeria, although legislation is pending.
Legislation or no legislation, Sammani Maimukulli, 50, now steers clear of herbal sex stimulants.
"I stopped using them seven years ago," he told AFP.
"I was given a strong potion by a herbalist and after taking it I became aroused but the erection refused to subside even after I made love to my three wives," he recounted.
"For four days my penis stayed erect and I had to be admitted to Ahmadu Bello Teaching Hospital in Zaria (140 kilometers away) where doctors told me that I stood the risk of becoming impotent.
"I stayed for more than a week and it cost me 50,000 naira (340 dollars). Since then I have refrained from any sex stimulant."